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Automobile Ignition

Operation, Upkeep, Care and Repair of
Modern Forms of Storage Battery
and Magneto Ignition Equip-
ment for Automobiles

By -a; ^
HAROLD Py MANLY

Author of '''AutomobOe Starting and Lighting*
Editor q£ Brookes' Automobile Handbook

ILLUSTRATED

CHICAGO

FREDERICK J. DRAKE & CO.

Publishers

Frbd*k J. Drake & Co.

PREFACE

Automobile Ignition is designed to meet a definite-
need for a reference and instruction book in which
may be found complete information covering all
phases of present-day ignition, either battery or mag-
neto.

While a non-technical explanation of theory and
principle is always given, the greater part of the work
is devoted to descriptions of, and instructions relat-
ing to, actual equipment in every-day use. This plan
allows principles, as well as practice, to be given in a
practical, rather than a theoretical way.

A great majority of the illustrations showing meth-
ods of construction and operation have been made to-
show the devices as built by the several manufactur-
ers; and, whenever possible, the name of the maker
has been given as an assistance to the practically in-
clined reader. Methods of adjustment and wiring,
both axtemal and internal, have been considered as:
of first importance in all cases.

Although the subject of modem ignition has been
treated in many of the newer works on electrical
equipment, it has always been treated as of somewhat
secondary importance ; while the author has found in
his experience that a majority of automobile workers
regard ignition as highly important. For that rea-
son, the entire volume has been devoted to this one
subject, and each principle of operation and method
of building has been considered only from the ignition
point 'of view.

The Author.

TABLE OF CONTENTS

OHAPTEB PAGK

I Electric Ignition 9

Types of Ignition — Time of Ignition — Spark
Advance and Retard — Spark Control.

II Electricity and Magnetism 18

Electrical Measurements — Polarity — Elec-
trical Connections — ^The Electric Circuit —
Magnetism — ^Electro-magnetism.

III Production of Electricity 33

Induction— <3urrent Sources — Dynamos — Stor-
age Batteries — Dry Cells — Ignition Combina-
tions.

IV Producing the Spark 50

Contact Breakers — Breaker Adjustment —
Breaker Cams — Breaker Arms and Levers —
The Condenser — ^The Distributor. ^

V The Ignition Circuit 77

Closed and Open Circuit Systems — Ignition
Coils — Resistance Unit — Safety Spark Gap —
Spark Plugs — Ignition Wiring.

VI Ignition Timing 113

Principles and Requirements — ^Methods and
Practice — Firing Orders — Distributor Wiring
and Timing; — ^Advance and Retard — ^Automatic
Spark Advance.

VII Battery Ignition Systems 156

Delco — ^Atwater Kent — Remy — Westinghouse
— Connecticut — Bosch — ^North East.

VIII Ford Ignition 246

The Magneto — ^Vibrators and Coils — ^The Com-
mutator — ^Wiring and Timing — Troubles and
Remedies — ^Master Vibrators.

TABLE OF CONTENTS
CHAPTER PAOE

DC Magneto Ionttion « 273

Principles of the Magneto — ^Types of Magnetos
— Starter Coils — ^Two Spark Ignition — ^Mag-
nets and Pole Pieces — ^Magneto Breakers and
Distributors.

X Magneto Timing, Wiring and Drive 304

Timing — ^Magneto Drive — Starter Couplings —
Magneto Mounting.

XI High Tension Magnetos 323

Bosch DU Magnetos — ^Bosch ZR Magnetos —
Bosch Dual Magnetos — ^Bosch NU Magnetos —
Eisemann 04 Magnetos — ^Eisemann EU Mag-
netos.

XII Transformer Coil Magnetos , 355

Principles — Remy Magnetos — Splltdorf Mag-
netos.

XIII Inductor Magnetos 363

Principle of Inductors — Remy Magnetop —
Dixie Magnetos.

XIV Location and Remedy or Ignition Troubles 378

Care and Maintenance — Lubrication —
Troubles Other Than Ignition — ^Testing Meth-
ods and Equipment — ^Voltmeters and Ammet-
ets — Circuit Tester — Spark Gap — Ignition
Faults and Remedies — Systematic Trouble Lo-
cation Tables.

AUTOMOBILE IGNITION

CHAPTER I

ELECTRIC IGNITION

The object of the whole ignition system of an auto-
mobile is simply the production of a small spark
about a fiftieth of an inch in length in the cylinder
of the engine, yet the parts required for producing
this spark are among the most interesting and highly
developed of all the units that go to make up the
completed car.

Many methods of ignition have been used, not all
of them electric, but all except one, the jump spark
system, have disappeared. This remaining system
makes use of a current of electricity having such high
pressure or voltage that it is capable of passing
through the highly compressed gas in the cylinder
and across the space between two metallic points as
shown at C in Figure 1. This passage of current
produces an electric spark of great heat and from
this spark the inflammable mixture of gasoline vapor
and air or the vapor of any other fuel is ignited
and the resulting combustion produces the pressure
and power that operates the car.

Early types of engines made use of fireproof tubes
maintained at incandescence by an external flarae

AUTOMOBILE IGNITION

and when the gas in the cylinder waa allowed to
come into contact with these tubes, ignition resulted.
This type is shown at A in Figure 1, Certain forms
of engines in use today ignite the combustible gases
by the heat resulting from high compression, the
Diesel engine being the best known example of this
method.

Stationary engines now in use, and early types
of automobile engines use the "make and break"
system of ignition shown at B in the illustration.
"With this method a current of low voltage and large
volume or amperage normally passes from a sta-
tionary contact mounted within the combustion space

ELECTRIC IGNITION II

of the engine cylinder to a movable contact likewise
carried inside of the cylinder. At the proper instant
these contacts are caused to separate by external
mechanism and the result of this interruption of
the flow of current is a hot spark at the contacts.
While the study of these obsolete methods would be^
interesting, it would be of no practical usefulness-
because cars using them have long since passed out
of use, therefore they are not considered in the fol-
lowing pages.

Modem forms of jump spark ignition may be
divided into three classes. The oldest class, and at
present the least used, is that known as the battery
system. This form was popular from the inception
of the present type of gasoline car and retained it&
position of importance until about the year 1907 or
1908. At that time the magneto was introduced on
a large number of cars that had not previously car-
ried it because of the high cost of this instruments
From that time until about 1914 the magneto domi-
nated the field almost to the exclusion of other forms*
With the advent of electric starting and lighting came
the new type of battery ignition that draws its cur-
rent supply from the lighting and starting battery
and from the lighting dynamo. At the present time,
while the magneto has its strong supporters and is
found on a great number of cars, the battery systems
are found in greater numbers than are magnetos.

TIME OF IGNITION

Engine Cycle, — The instant at which ignition is
offected is an important point in the cycle of opera-
tions through which the internal combustion erv^lx^a^

AUTOMOBILE IGNITION

passes. Those familiar with this class of work know
that the type of engine usually employed makes use
of the four cycle principle in which four strokes, as
shown in Figure 2, are required to perform the neces-
sary "operations. The first stroke is called the inlet,
during which fresh gas is drawn into the cylinder
and the second is the compression during which the
gas is forced into the combustion space, and. at the

Inlet Compression Poorer Exhaust

Figrure 2.— Strokes of a Four Cycle Engine.

«nd of which comes the ignition point or time at
which the compressed gas is ignited. During the
third stroke of the piston the burning gas expands
And on the fourth and final stroke the spent charge
is exhausted.

It is at some time during the compression stroke,
or at the end of this stroke, that the gas must be
ignited. The exact instant at which the spark occurs
depends on several factors, but in all cases the object
sought is that the entire charge will be fully aflame
and at the point of greatest pressure when the piston

eijEctric ignition IB

has reached the top of its stroke and is ready to
descend on the power stroke.

The space occupied by the gas when compressed
is of considerable volume but in the usual design
it is only at one small point in this space that th&
ignition spark takes place. Rapid though the travel
of the flame may be, an appreciable time is required
for the whole charge of gas to become fully ignited
and to reach its point of greatest pressure. The
ignition flame starts in ' the gas immediatefly sur-
rounding the spark and finally reaches the farthest
points of the combustion space in the cylinder.

During this time of flame travel, the piston of
the engine is moving with greater or less rapidity
up or down in the cyUnder, the piston speed depend-
ing on the number of revolutions that the crank
shaft is then making in a given length of time. In
order that the engine may develop the greatest pos-
sible power from the amount, of fuel being used it is
necessary that the gas be ignited at such time aa
will insure ma^simum pressure immediately after the
piston starts on its down stroke.

Should the ^ gas become fully ignited while the
piston is still traveling upward on the compres-
sion stroke, a strong downward force would be ex-
erted, tending to retard the speed of the engine and
greatly reducing the power output

On the other hand, should ignition fail to take
place until the piston had reached the top and again
started on its downward stroke, the gas would have ,
lost much of its power possibilities because of the
reduced degree of compression. The power and pres-
sure of the burning gas is in direct proportion to
the compression pressure of the gas when i^ait^

14 AUTOMOBILE IGNITION

And the cylinder is so designed that the stroke of
the the piston causes the correct degree of compres-
sion. If ignition takes place too late, part of this
<;ompression pressure is lost with a resulting lower-
ing of the power output and economy.

When the piston is traveling very slowly, as for
instance, in the cranking operation, the gas will fully
ignite before the piston has traveled more than a
very little of its stroke and the spark can safely
take place practically at the same instant that full
ignition is desired, this being when the piston is at
the top of its stroke.

If the time at which the spark passes is not changed
according to the engine speed, and if the engine is
then run very fast, full ignition will not take place
until the piston has started on its down stroke with
the results already outlined.

With an engine having a stroke of 5 inches and
running at 2,000 revolutions a minute, the piston
epeed will be 20,000 inches a minutes or 333% inches
€ach second. In 1/100 part of a second the piston will
have passed from its uppermost position, 3% inches
down on its stroke and if the rate of flame travel
requires this 1/lOOth of a second to fully ignite the
gas the power stroke will be two-thirds completed
before full ignition takes place. To cause complete
firing of the charge and full generation of pressure
to take place with the piston at the top of its stroke,
it is necessary that the spark pass earlier and earlier
during the compression stroke as the engine speed
increases, so that the full force of the burning gas
may be available at the desired time. This change in
time of ignition is effected in various ways which will
be described in detail.

ELECTRIC IGNITION 15

ADVANCE AND RETABD

While the interval required for travel of the flame
through the mixture is the chief reason for causing
the spark to take place at varying times; there are
other considerations that also call for this advancing
or retarding.

One of these reasons is the mechanical lag that
exists in the ignition apparatus. The action of a
number of mechanical parts is required in order to
generate the electrical pressure for the spark at
the time it is needed. No matter how sensitive, how
light and how accurately these parts may be made;
they require a certain length of time for their opera-
tion and due to the extreme speed of the engine
piston, this time must be allowed for in determining
the instant at which the spark should occur/

In addition to the mechanical lag there is also
what is known as electrical lag. Two distinct elec-
trical currents are required in the production of the
spark, one of these currents acting in such manner
as to produce the other one. Between the effect of
one current and the generation of the other there is
an interval and this also must be cared for by advanc-
ing the spark time.

We have now seen that variation of the time for
the spark, when considered in relation to the stroke
of the engine piston, is affected by the time required
for spread of the flame, by the mechanical lag and
by the electrical lag. There is one more considera-
tion that may call for an earlier or later spark, this
being the proportion between air and gas in the

vapor that makes up the mixture in the cylinder. If
this mixture is composed of certain proportions of

16 AUTOMOBILfB IGNITION

air and gas, the burning will be extremely rapid and
the spark advance need not be so great as with a
slower burning mixture. If, however, the propor-
tion of air becomes either greater or less than the
ideal condition, the mixture will not bum so fast
and the time of sparking will require advancing.

SPABK CONTROL

In order to cause the electric spark to pass through
the inflammable mixture at such time as to produce
complete ignition of the charge when required, a
majority of systems provide means for altering this
time to correspond with engine speed. All of the
systems in which such means are provided are in-
cluded in the class known as variable spark ignition
systems. In some of these types the spark timing
is controlled by the driver and this form is given
the name of hand or manual control. In others the
timing of the spark is changed mechanically by some
form of governor and these are known as automatic
advance systems.

Many magneto installations have been made with-
out provision for altering the time at which the spark
passes and this type goes by the name of set spark
ignition. With set spark ignition the permanent
advance is made sufficient to care for all average
conditions of operation.

While the set spark method causes ignition to
commence considerably before the piston reaches top
center, no ill effects are encountered even while crank-
ing the engine because of the fact that when the
cranking is done at speed sufficiently high to cause
the magneto to generate current enough for a spark,

ELECTRIC IGNITION 17

the flywheel is travelling fast enough to require
such an advance and the power impulse takes place
as usual. Set spark ignition has the advantage of
simplicity because of the absence of control mem-
bers and will give better average operation than
will improper spark manipulation by a careless or
ignorant driver. This method has the disadvantage
of gfving perfect operation only over a very limited
range of engine speed.

CHAPTEE II

ELECTRICITY AND MAGNETISM

Electricity cannot be satisfactorily defined because
of the fact that it cannot be seen, heard, weighed or
otherwise directly measured.' It is true that many
of the effects of electricity can be seen, heard and
felt ; but these are only effects and are not electricity
itself. We can only say that electricity is the force
ivhich causes electrical effects.

For convenience in explaining electrical effects we
Assume that electricity flows through materials called
<ionductors and this flow is called the electric cur-
rent. The various effects of the electric current may
be measured so that it is possible to explain matters
in terms of pressure, volume, quantity and other
<»onvenient values.

The two measurements that are most used in speak-
ing of the electric current are its pressure, defined in
volts, and its rate of flow, measured in amperes. It
is also necessary to measure the degree of resistance
,with which any material opposes the passage of an
electric current through itself and this resistance is
measured in ohms.

Voltage or pressure acts to send the current

i through conductors and the rate and volume passing

through the conductor in a given time is measured in

^ amperage. An increase of pressure or voltage will

r 'Cause a (?^rresponding increase in flow or amperage

ELECTRICITY AND MAGNETISM 19

provided the resistance remains the same, while a
reduction of voltage will allow a consequent reduc-
tion of amperage.

The best conductors, that is, those having the least
resistance, are metals of all kinds. Other materials
which have extremely high resistance to the passage
of electric current are called insulators and include
such substances as glass, mica, porcelain, stone, wood,
paper and cloth.

The resistance of any conductor (Jepends on its
size around, or cross sectional area, and on its length.
The resistance becomes less as the size of the con-
ductor becomes greater, presenting a greater mass at
any given point. The resistance is increased as
the length of a conductor becomes greater, presenting
a longer pathway through which the current must
force itself. The resistance is also affected by the
kind of material in the conductor and by the tem-
perature of the parts through which the current
passes, high temperatures generally causing an in-
crease in resistance.

With the voltage or pressure remaining the same,
an increase of resistance in the path of the current
causes a reduction of amperage or flow, while a de-
crease of resistance with constant voltage allows the
amperage to increase.

The pressure, measured in volts; the flow, meas-
ured in amperes; and the resistance, measured in
ohms, bear a definite relation to each other so that,
knowing any two values for a circuit, the third may
be easily found.

One volt is the pressure required to cause a flow of
one ampere in a conductor against a resistance of
one ohm.

20 AUTOMOBILE IGNITION

One ampere is then the flow caused in a conductor
by a pressure of one volt acting against a resistance
of one ohm.

One ohm is the resistance which will allow a cur-
rent of onQ ampere to flow in a conductor under a
pressure of one volt.

Voltage may be determined by multiplying the
number of amperes by the number of ohms.

Amperage may be found by dividing the number
of volts by the number of olims.

The resistance in ohms may be found by dividing
the number of volts by the number of amperes.

POLARITY

The theory which assumes that electric current
flows through conductors also assumes that this flow
has a certain direction of motion. Any flow of cur-
rent must start from its source and after doing the
desired work must again return to the source, keep-
ing up this flow until the current is interrupted.

Every source of current therefore has two parts,
one from which the current flows and the other to
which it returns. The side from which the current
starts from the source is called the positive, and the
side to which it returns is called the negative.

Flow of current is caused by electrical pressure
measured in volts. In order that there may be a
flow of current there must, therefore, be a difference
of pressure between two points, and this difference of
pressure will cause a flow of current from the point
of higher pressure to other points of lower pressure.
The points of high pressure are said to be positive
and those of lower pressure are said to be negative.

ELECTRICITY AND MAGNETISM

The earth itself is considered as having no electrical
pressure or zero pressure. Any point having greater
pressure than that of the earth is called positive,
while all points having pressure below that of the
earth are negative.

Current flow, as shown in Figure 3, is always away
from a positive point and toward a negative point
while outside of the source. Points which are posi-
tive are marked with a plus sign (+) or with the
letters '*POS'' or "P,'' and points which are nega-
tive are marked with a negative sign ( — ) or with
the letters '*NEG'' or **N''.

Figrure 3. — Path of Current in the Electric Circuit.

ELECTRICAL CONNECTIONS

The electric current from any source leaves from
the positive side and, as has been explained, returns
to the negative. Between the positive and negative
sides the current may follow a path through one or
more conductors and electrical devices of various
kinds.

Should all of the current from the source pass first
through one part of the path and, without any of the
current being diverted, pass in succession through all

22 AUTOUOBILB IGNITION

of the devices and other conductors before rctaming
to' the negative side of the source, all of the parts
outside of the source are said to be connected with
each other and with the electrical source in a series
connection, this arrangement being shown at the top
of Figure 4,

FlBTure i. — Series and

A series connection may then be defined as a con-
nection made between several sources of current or
between several current consuming devices in such a
way that all of the current that passes through any
one unit or conductor will also have to pass through
every other unit and conductor in the circuit. In the
case of parts having definite polarity the positive
side of one will be connected with the negative of the

ELECTRICITY AND MAGNETISM 25

next and the positive of this second part with the
negative of the third and so on.

If, after leaving the source, the current divides
and part of it takes one path while .the remainder
takes another path or several other paths before
returning to the source, the parts or various paths
carrying the current are said to be in shunt with
each other and the connection is called a shunt.
Such a connection is shown at the bottom of Figure 4.

A shunt is therefore a path thrpugh which only a
part of the whole current flows, the balance passing
through one or more additional pathp attached to the
first path or to the source.- Some forms of shunt
connections are called multiple or parallel.

THE ELECTRIC CIRCUIT

Probably the greatest of all difficulties encountered
by those studying or working with electrical matters
is due to a lack of complete understanding of the
requirements of the electrical circuit.

An electric circuit is defined by Houston as, **the
path in which electricity circulates or passes from a
given point, around and through a conducting path,
back again to its starting point.'' It is in the last
words of this definition, *'back again to its starting
point," that the difficulty occurs.

The starting point of the electric circuit in igni-
tion work is either a magneto, a lighting dynamo or
a battery. From the starting point the current flows
through conductors, usually of wire, through various
parts of the ignition system such as coils, switches
and spark plugs, and must then return', either by an-
other wire or some metallic path to the source. It is

24 AUTOMOBILfB IGNITION

not enough that the current flow from the battery
or magneto, to the several parts of the system, but it
must also return again to the battery or magneto.

If for any reason there is not a complete path back
to the source from the devices in the ignition system,
the circuit is broken and there can be no flow of elec-
tricity and no electrical action whatever in any part
or parts having to do with ignition.

In looking for electrical trouble the experienced
repairman or electrical worker will first trace the
complete circuit. He will start from the source
(magneto or battery) and follow the conductors to
the first device in the system to which current fiows.
Making sure that the flow passes through this device,
he will follow to the next and so on for the entire
installation. Having reached the last part of the
circuit, the conducting path, either through wires or
other metallic parts of the car, will be followed until
it again reaches the source from, which a start was
made.

Some common forms of trouble are shown in Fig-
ure 5. Should there be any interruption at any point
in the circuit, the whole system will be dead and
there is said to exist an open circuit as at 0. If, at
any point in the system, as at S, it is possible for the
■current to find its way through other conductors than
those intended, and to travel back to the source with-
out going through the ignition parts and doing its
proper work, the trouble is said to consist of a short
circuit by means of which the current finds a shorter,
easier return path and therefore fails to accomplish
the desired result.

It is commonly found that those investigating
causes for trouble in ignition systems will carefully

ELECTRICITY AND MAGNETISM

25>

trace a part or several parts of the circuit, but will
fail to go all the way around and back to the source,
thus making all that part of the work properly done
of no avail because of a failure to complete the
tracing.

It has already been stated that any metal forms an
excellent electrical conductor and this fact makes it
possible to use the metal work of the car and engine

SOi//fC£

FIgrure 5. — Troubles in Wiring. G: Ground. O: Open CircuiC

S: Short Circuit.

for carrying one side of the ignition circuit, either
positive or negative, while the other side is carried by
insulated wires and electrical devices. In Figure &
the magneto is shown grounded to the base on which
it rests and a large part of the return circuit from
the coil to the magneto is carried through this metal-
lie path. -The magneto is then said to be grounded
and one terminal of the coil is likewise grounded
80 that they are electrically connected. These con-
nections are normal grounds and are necessary to the
operation of a system so designed.
Accidental grounds may occur as shown at G in

26 AUTOMOBLLB IGNITION

Pigure 5. These are abnormal grounds and inter-
fere with the proper operation of the system. Such
« ground is a form of short circuit and may be lo-
•cated by much the same means as use^ in finding
fihorts, bearing in mind that the metal of the car
forms one side of the circuit while the wiring and
electrical devices form the other.

A great majority of all ignition trouble is caused
either by open circuits, short circuits or grounds. In
order to determine properly the specific cause for
these faults it is necessary to understand electrical
principles and the application in the particular sys-
tem being investigated, but the greatest aid of all in
locating and remedying such trouble is to conscien-
tiously trace the circuit from the source to the igni-
tion units and then back to the source.

MAGNETISM

A piece of iron or steel may be made a magnet
through the influence of another piece that is already
magnetic or by being acted upon by the electrical in-
fluence from a conductor carrying current. A mag-
net shows attraction for another magnet or for any
piece of iron or steel that is near it.

Magnetism, like electricity itself, can only be de-
nned and described by telling of its action and effects.
In order to allow a ready explanation of these effects
many theories have been advanced as to the nature of
magnetism. Like all ideas that remain theories, none
of these have been proven correct, but, inasmuch as
they serve the purposes of explanation, they have
been accepted on this understanding.

The magnetism in a piece of iron or steel is sup-

ELECTRICITY AN1> MAGNETISM

posed to consist of a circuit, and the path of this cir-
cuit through the magnet and the space immediately
surrounding it is called the path of the magnetic
lines of force.

These lines of force pass through the metal of the
magnet from one end to the other and after issuing

Figure 6. — The Field of a Magnet.

from the magnet travel through the surrounding
space to re-enter again, thus keeping up a continuous
travel or magnetic circuit, as shown in Figure 6.

The end of the magnet at which the lines of force
enter the mot«i is called the South or negative pole.

28 AUTOMOBILE IGNITION

while the end from which the lines of force leave tt
metal is ^lled the North or positive pole. The spac
through which the lines of force travel while outsid
of the magnet is called the magnetic field of thi
magnet.

While all metals are good conductors of electri
current, only iron, and its common form, steel, ha\
the ability to become magnets. It is true that ther
are two other metals, nickel and cobalt, which ar
slightly magnetic in their properties, but for pra(
tical. purposes, and in the study of electrical ignitioi
we may say that iron and steel are the only material
that can be made magnetic.

Magnetic lines of force reside in and act only f roi
iron and steel, but they will easily pass through othe
materials of all kinds almost as though these othe
materials were not in their pathway. A magnet ma;
be held on one side of a piece of glass and will attrac
another magnet or a piece of iron through the glasj
and the same action will take place through wooc
other metals or any material regardless of its prop
erties as an . electrical conductor or insulator. Tb
only way in which magnetic lines of force or mag
netism may be controlled is by providing pathways o
iron or steel through which this force may travel an(
there is no substance by means of which magnetisr
may be confined as may be done with the electric cui
rent when confined by insulators.

A piece of hardened steel which is made a magne
has the power to retain the magnetism for a louj
period of time unless acted upon by outside force
such as hammering or heating. Such a piece o
hardened steel is then called a permanent magnet.

A piece of soft iron or very soft steel will not re

ELECTRICITY AND MAGNETISM 29

tain magnetism to such an extent as will these same
materials when hardened. These metals, when soft,
carry the magnetic lines of force as readily as when
hardened but are magnetic, and have the properties
of magnets, only while in the magnetic field of other
magnets or of coils of wire carrying current which
produces magnetism.

A piece of soft iron in contact with, or very close
to, a magnet, has all the properties and characteristics
of ^ magnet and will then attract other pieces of iron
or steel and other magnets. As soon as this piece of
soft iron or steel is removed from the magnetic field
of the other magnet it loses almost all of its magnet-
ism, the degree of loss depending on the softness of
the metal.

When two permanent magnets are brought close
together they manifest certain peculiar activities with
reference to each other. If they are presented in
such a way that the positive pole of one is near the
negative pole of the other, there is a very strong at-
traction and the two magnets tend to pull together
and when in contact to hold each other.

.Should, however, these two magnets be presented
to each other in such a way that the positive pole of
one is near the positive pole of the other, or in such
a way that the two negative poles are together, there
is not only a lack of attraction, but a repulsion or
tendency to stay apart and some effort is required to
isause the two poles to remain in contact. From these
tendencies the following rule has been deduced : Un-
like poles (positive and negative) attract; like poles
(two positives or two negatives) repel each other.
If different poles of one magnet are known as posi-
tive and negative, the poles of another magnet may

30 , AUTOMOBILE IGNITION

be^ easily identified because the positive of the knowi
magnet will attract the negative of the other, an(
vice versa.

If two magnets of similar shape be placed togethe:
with their like poles touching, two positives togethe:
and two negatives together, the magnetic strengtl
will be increased and the compound magnet thu
formed wiU have greater strength than a single mag
net of the same weight as the two together.

If two magnets of similar shape be placed togethe:
with the positive of one next the negative^ of the othe:
the magnetic lines of force of one magnet will issu)
from its positive pole and enter the negative pole o:
the other, passing through this other magnet and ou
of its positive pole into the negative of the first one
In this way there is no magnetic field or lines o:
force outside of the metal of the two magnets and a
far as useful work is concerned they neutralize th
magnetic effect, each of the other.

Magnets are made in many different shapes an(
forms, depending on the machine with which usee
and their intended purpose. Some forms are showi
in Figures 109 and 124. In magnetos the most com
mon form is the horseshoe magnet, which is shapec
like the capital letter U. Others are formed in par
of a circle, like the letter C, others are V shaped, stil
others are formed like a bell and so on. The prin
ciples governing the action ^f a magnet are not al
tered by its shape, but the various forms are utilizec
in order that the magnetic field may be brought t(
the desired size or position to produce the prope:
action. The straight bar magnet is not used in igni
tion for the produistion of a magneto field, because o:
its widely separated poles.

ELECTRICITY AND MAGNETISM

ELECTRO-MAGNETISM

A conductor through which is flowing an electrie
current is surrounded by circular lines of force which
seem to whirl around the length of the conductor as
a center or axis. These lines of force always travel
around the conductor in one given direction relative,
to the direction of current flow through the conduc-
tor. If the current flow is reversed through the con-
ductor the direction of travel of the lines of force
around the conductor is also reversed.

If a piece of iron or steel be brought into the path
of this magnetic field which surrounds the electrical
conductor, as in Figure 7, this piece of iron or steel

'V\\\\»

Figure 7. — Current and Field of Electro-Magnet.

will become magnetized. Its degree or strength of
magnetization depends on the strength of the mag-
netic field surrounding the conductor.

To produce a strong magnetic effect in iron or
steel the current carrying conductor is wound around
the metal so that the lines of force of the conductor
completely surround the iron or steel which is ta
be magnetized. The lines of force around the con-
ductor then take their path through the iron or steel
which is called the core of the combination which
has become an electro-magnet. The direction of the
magnetic lines of force through the core of the elec-

32 AUTOMOBILE IGNITION

tro-magnet depends on the direction of current flow
through the winding and on the direction in which
the conductor is wound around the core. The strength
of the electro-magnet depends on the amperage of
the current flowing through the conductor and on
the number of turns of the conductor around the
magnet core.

The core of an electro-magnet is made from very
:soft iron, usually in the form of lengths of wire or
of thin sheets rather than in one solid piece. Such
a magnet retains its magnetism only as long as cur-
rent flows through its winding and upon stoppage
of the current practically all of the magnetism and
the magnetic field of the electro-magnet disappear.
A small amount of magnetism remains in the core
no matter how soft the iron may be and this remain-
-der is called residual magnetism.

CHAPTER III

PRODUCTION OF ELECTRICITY

In order to produce a spark within the cylinder
of the engine it is necessary, that the electric current
jump across a small gap which is inside the cylinder
and surrounded by the gaseous mixture. A current
of extremely high pressure or voltage is required in
order to pass across this gap because the resistance
of the mixture is so great that no ordinary voltage
has any effect. The pressure of the current from
any of the primary'' sources used for ignition is never
more than from six to fifty volts, but this current of
low voltage is of compartively great volume or
amperage, and is used to produce another current
having voltage suflBciently high to pass across the
gap, through the mixture, and in so doing produce
the heat of the electric spark.

The required high voltage or high tension current
is secured by induction from the primary current
which is of comparatively low voltage as received
from the electrical source.

Should the core of an electro-magnet be extended
this extended portion would, of course, have the same
magnetic qualities as would the balance of the mag-
net. A conductor coiled around the extended core
would then be in the magnetic field of the electro-
magnet and would be infiuenced by changes of
strength in the magnetic field.

AUTOMOBILE IGNITION

It has been found that any change in the strength
of a magnetic field within which is a coil of wire
will cause electric currents to be induced in the coil,
the strength of these currents depending on the in-
tensity of the magnetism, and on its degree of change.

In actual practice the second coil of wire in which
is to be induced the high vbltage current is generally
wound around the outside of the primary coil already
on the electro-magnet. The double coil with its core
is then called an induction coil. The winding through
which passes the current from the source of electri-

SCt/^C£

FlfiTure 8. — Principle of the Induction Coll.

city is called the primary or low tension winding
and the coil wound outside the primary* is called
the secondary or high tension winding. The current
which passes through the primary winding is called
the primary current and that which passes through
the secondary winding is called the high tension or
secondary current, the relation of these parts being
shown in Figure 8.

When a current of comparatively low voltage is
passed through the primary winding of the induction
coil there is a current generated in the secondary

PRODUCTION OF ELECTRICITY 35

winding. This current which is induced by comple-
tion of the primary circuit is not of sufficient strength
to cause a spark in the cylinder.

When, however, the circuit through the primary
winding is broken and the current ceases to flow
thei'e is a very powerful action in the coil and a high
tension current is induced in the secondary winding
with sufficient voltage to cause the current to pass
across the spark gap and ignite the mixture.

The pressure or voltage of the secondary current
is greater than the voltage of the primary current
in proportion to the number of turns of wire in the
secondary winding as compared with the number of
turns in the primary winding, less the loss due to
the transfer of energy. The primary current is of
low voltage and rather high amperage, while the
secondary current is of extremely high voltage and
very low amperage. The primary winding consists
of a small number of turns of large size wire and the
secondary winding consists of a great number of turns
of fine wire.

The induction coil is usually called a spark coil
or else a transformer coil. The name transformer
coil is not,. strictly speaking, the correct one because
a transformer coil is used to produce a low voltage
current from one of high voltage. Usage has made
the name transformer coil apply to the induction
coil used in ignition so that this name is now accepted.

CURRENT SOURCES

There are four commonly used sources of current
for ignition. The source found on cars equipped with
electric lighting and engine starting systems is in

36 AUTOMOBILE} IGNITION

most cases the dynamo which is provided for the
lighting and starting functions. This dynamo is an
instrument which converts a part of the mechanical
power of the engine into electrical energy. With the
engine of such ft car idle the source of ignition cur-
rent used while starting the engine and for running
at low speeds is the storage battery which has been
previously charged from the dynamo. This battery
is an electro-chemical device in which chemical
changes are caused to take place by the current from
the dynamo and in which a reversal of these chemical
changes causes a flow of electric current from the
battery.

On a great many cars the electrical source consists
of a magneto of any one of the several well developed
forms. A magneto is a form of dynamo-electric
machine especially adapted for the production of
current suitable for ignition but not suited for the
pl*oduction of a current that will charge a storage
battery. The current from a magneto is alternating,
and periodically changes its direction of flow; while
from a dynamo, the flow is direct and does not reverse
its travel.

For an emergency or as an auxiliary source of '
ignition current many cars use batteries of dry cells
which may be switched into the ignition circuit when
desired. Dry cells are no longer used as the principal
source of current for ignition although at one time
they were very commonly found.

DYNAMOS

The dynamo used for battery charging consists
of two elements, one revolved by the engine while

PRODUCTION OP BLBCTRICITT «I

the other ia stationary. The rotation of one part
. causes an electric current to flow in the part which
is called the armature. The necessary magnetism is
provided by the field magnets.

In the usual construction as shown in Figure 9
the armature rotates while the field magnets are sta-
tionary. The armatare consists of a number of coils
of wire wound on a core of soft iron discs while the
field magnets consist of soft iron cores with windings

FIELD

Figure 9. — Principal Parts of the Dynamo.

which make the cores electro-magnetic. Rotation of
the armature with its coils between the ends of the
field magnets causes a change of magnetism in the
armature coils such that a current flow is induced
in these eoib in somewhat the same manner as a flow
of currait is induced in the induction coil.

From the armature of the dynamo the current
passes to a commutator which causes the current
flow in the outside wiring to be always in the same
direction and it is called a direct current. The
reversal of magnetic flow through the armature coils

38 AUTOMOBILE IGNITION

generates a current which first flows in one direction,
then in the other as the change occurs, this form of
current being known as alternating. An alternating
current cannot be used for charging a- storage bat-
tery and for this reason the flow is changed to direct
by the commutator.

In contact with the dynamo commutator are two
or more brushes which collect the current and to
which are attached wiring connections. These con-
nections lead from the dynamo through the current
regulating and controlling devices to the storage bat-
tery where the current is used for charging. The
action, characteristics and operation of the dynamo
are not strictly parts of the ignition subject and afe
therefore not treated at length here.

STORAGE BATTERIES

The storage battery as shown in Figure 10 con-
sists of a number of cells or parts, one cell for each
two volts pressure secured from the battery as ordi-
narily used. Each cell is composed of a number of
plates, part of the number being of positive polarity
while the remainder are negative. All of the posi-
tive plates of one cell are connected together and all
the negatives are likewise connected. The positive
plates are then attached to the positive terminal of
the cell and the negative plates to the negative ter-
minal. The plates in a cell are prevented from com-
ing into contact with each other by thin sheets called
separators.

To bring the battery plates into condition for

causing a flow of current, electricity must first flow

through them from the dynamo. X e\vereL\Q-vi\ ^oXAftw

PRODUCTION OF ELECTRICITY , 30

,then takes place between the plates themselves and
a eolation of sulphuric "acid and water in which they
are immersed. In making 'this change the energy

of the dynamo current is consumed and the plates
are then ready to cause a flow of current from the
battery by which the energy is made to re-appear.

40 AUTOMOBILE IGNITION

With a flow of current from the battery the plates
revert to their former condition and a further flow
of dynamo current is required to charge the battery.

The liquid in which the plates are immersed is
called the battery electrolyte and is composed of pure
distilled water and sulphuric acid in certain pro-
portions. As the battery discharges its current, a
part of the acid combines with the material in the
plates so that the electrolyte becomes more like water
and weaker in acid strength. Charging of the bat-
tery from the dynamo current again causes the elec-
trolyte to become stronger in acid.

It will be seen that the condition of charge or
discharge of the battery is indicated to a great extent
by the acidity of the liquid around the plates. The
acid is much heavier than water and as the pro-
portion changes the electrolyte becomes lighter as
the battery becomes discharged and heavier as it is
re-charged.

The strength or weight of the electrolyte is meas-
ured with a hydrometer shown in Figure 11 which
consists of a weighted glass tube with a graduated
scale at its upper end. This hydrometer is generally
carried inside of a tube which is fitted with a rubber
bulb at one end and a nozzle at the other. The com-
bination is then called a hydrometer syringe.

The scale is graduated to read the specific gravity
of the electrolyte; that is, to measure the weight of
the liquid relative to the weight of an equal quantity
of pure water. Markings on the scale run from
1.000 near the top to 1.400 near the bottom. In using
the hydrometer the bulb is squeezed in the hand and
the nozzle dipped below the surface of the electrolyte
JJ2 the cell to be tested. As tke px^sviT^ o\v\)cL^\$v3J3a

PRODUCTION C

' ELECTRICITT

is released the liquid is drawn up into the ayringe
and the hydrometer floats. If the liquid is very
heavy, indicating that the battery is well charged,
the hydrometer will not sink very deep into the liquid

while if the acidity is slight and the liquid compara-
tively light, showing that the battery is nearly dis-
charged, the hydrometer will sink to a greater depth.
The point on the hydrometer scale which remains
at the surface of the electrolyte in the syringe indi-

42 AUTOMOBILE IGNITION -

fcates the specific gravity of the liquid. If this read-
ing is greater than 1.250 the battery is well charged.
If the gravity is between 1.200 and 1.250 the cell is.
at least half charged. Gravity between 1.150 and
1.200 indicates that the cell is nearly discharged while
gravity below 1.150 mean? that the cell is discharged.
A discharged cell will not provide satisfactory igni-
tion and the charging system should be given the
needed attention.

The following notes on the care of storage bat-
teries are taken from the instructions issued by the
Society of Automotive Engineers : Keep the battery
terminals and connections coated with vaseline or
grease. If the solution has slopped or spilled, wipe
off with waste wet with ammonia water. In filling
cells do not use acid or electrolyte, only pure water
which is known not to contain even small quantities
of salts of any kind. Distilled water, melted artificial
ice or fresh rain water are recommended. Add water"
regularly, although the battery may seem to work all
right without it.

The best way to ascertain the condition of the
battery is to regularly test the specific gravity (den-
sity) of the solution in each cell with a hydrometer.
A convenient time is when adding water, but the
reading should be taken before, rather than after, the
water is added. A reliable specific gravity test can-
not be made after adding water and before it has
been mixed with the solution by charging the battery
or by runninc^ the car.

When all cells are in good order, the gravity will "
test about the same (within 25 points) in all. Put-
ting acid or electrolyte into the cells to bring up the
specMe gravity can do no good and may do great

PRODUCTION OF ELECTRICITY 43

harm. Acid or electrolyte should never be put in the
battery except by an experienced battery man. Grav-
ity in one cell markedly lower than in the others,
especially if successive readings show the difference
to be incfi*easing, indicates that the cell is not in good
order. If this cell also regularly requires more water
than the others, a leaky jar is indicated. If there is
no leak and if the gravity is, or becomes, 50 to 75
points below that in the other cells, a partial short-
circuit or other trouble within the cell is indicated.

DRY CELLS

The dry cell forms a valuable means of securing
a reserve supply of current because it is durable,
reliable, light in weight and small in size. As a
continuous supply for ignition current the dry cell
would today be a failure because of its limited ca-
pacity, but while starting the engine and in emergen-
cies its usefulness is undoubted.

The cell consists of a cylinder of zinc inside of
which is carried a carbon rod and with a filling of
finely powdered carbon and black oxide of manganese
between the zinc shell and ^he carbon. Saturating the
filling between the carbon and zinc is the electrolyte
or exciting liquid of the cell which varies in compo-
sition according to the ideas of the manufacturer.

The zinc can is lined wnth a layer of some porous
material, such as blotting paper, which holds a large
proportion of the electrolyte and keeps the liquid
in close contact with the zinc. The top of the cell
is tightly closed with a sealing compound which
prevents loss of the liquid by evaporation. The cell
as thus far described is carried inside of a cardboard

44 AUTOMOBILE IGNITION

cover which is either cylindrical or square. This
cover is the insulator for the zinc element and it must
be preserved without opening or breakage except at
the top, otherwise the cell will probably be short
circuited on other cells or the metal of a box -in which
it may be carried. One terminal to which a wire
may be secured is fastened to the upper edge of the
zinc shell and another terminal to the carbon rod in
the center of the cell. The terminal on the carbon
is of positive polarity and from it the current flows,
while the zinc terminal is negative and into this
terminal flows the returning current form the outside
circuits.

A single dry cell is capable of causing an electrical
pressure of II/2 volts. This pressure is the same
whether the cell be large or small in size. The rate of
flow or the amperage that may be taken from a dry
cell depends on its size, being greater in a large cell
than in a small one. The size generally used is called
a number 6, is 2i/^ inches in diameter and 6 inches
high. The maximum current drawn from this size
cell should not exceed one-half ampere if its maxi-
^mum practical life is to be secured.

The life of the dry cell is determined by the rate
of discharge and by the length of the periods between
use. A cell will give a flow of fifteen or more amperes
provided the resistance of the outside circuit is low
enough to allow the pressure of l^/^ volts to cause this
flow. In this case, however, the life of the cell would
only be a few minutes. With a low discharge rate,
such as one-half ampere, the cell will last for fifty
or sixty hours of intermittent use. A dry cell gives
best service under conditions which allow it fairly
long periods of rest between periods of current with-

PROD-UCTION OF ELECTRICITY 45

drawal, these periods allowing recuperation and a
renewal of its ability to do work.

While the cell is delivering current, hydrogen gas
is generated by the internal action. This gas is an
insulator and it reduces the current output of the
cell. The formation of the gas is called polarization
of the cell. The mixture of carbon and oxide of
manganese is called a depolarizer and from it is
liberated oxygen gas which combines with the hydro-
gen and forms water during the time the cell is at
rest. The removal of the hydrogen gives the cell
new life and it will again give its normal output.

The ignition systems in general use require a
greater voltage for the primary circuit than may be
secured from a single dry cell and in order to obtain
this voltage a number of cells are connected with
each other in series as shown in Figure 12. In a
series connection the carbon or positive terminal of
one cell is connected with the zinc or negative of the
second, the positive of this second with the negative
of the third and so on for the whole number of cells
in the series. The voltage between the carbon posi-
tive terminal of one end cell and the zinc negative
terminal of the cell at the other end of the series
Vill now be approximately equal to the voltage of one
cell, which is li/2> multiplied by the number of cells
connected together. Thus, four cells will provide
six volts ; eight cells will provide twelve volts and so
on for any number. In practice it is customary to
add one more cell than called for by this rule, the
added cell's pressure making up for the additional
resistance of the parts and connections of the series.

"While a series connection of dry cells increases the
voltage it does not increase the flow or amperage that

AUTOMOBILE laNITlON

may safely be taken from the battery. In order to
increase the available amperage the cells are con-
nected in multiple or shunt with each other. Thia
multiple connection, also shown in Figure 12, is made i
by eonneeting together all of the negative terminals
of several cells and then connecting all the positive
terminals with another wire. The voltage of any
number of single cells in multiple would still be only

S£/ll£S-Ml/LT/PLE

as great as from one cell, or IVg volts, but it is allow-
able to draw an amperage equal to the allowable
amperage from one cell multiplied by the number
of cells in the group so connected.

When it is desired to increase the voltage and
also to increase the amperage the dry cells are con-
nected in series-multiple. In using this method of

PRODUCTION OF ELECTRICITY 47

connection a sufficient number of cells are connected
in series to provide the required voltage and two or
more of these series batteries of cells are made up.
The end negative terminals of the several batteries
are then connected with each other and the several
end positives are likewise connected together as also
shown in Figure 12. From the wires used for making
this multiple connection may be secured a voltage
equal to the pressure of one of the series sets and an
amperage equal to the number of sets multiplied by
the amperage of one cell. The life of a given number
of cells connected in series-multiple is much greater
than would be the life of a number of series sets
used one at a time following each other. Thus the
life of one series-multiple set of ten cells connected
in two series batteries of five cells each will be more
than twice the life that would be secured from one
of the series sets of five cells when used alone.

IGNITION COMBINATIONS

Various names denoting certain combinations of
magnetos and battery systems have come into use
and have been generally accepted. These combina-
tions are described in the following paragraphs.
* An engine is said to be provided with single igni-
tion when the sole source of current is a magneto
or else a battery. An engine having a magneto only
is fitted with a single ignition system or an engine
having only a battery and dynamo is said to have
single ignition.

Should an engine be fitted with a magneto and all
of the other parts required for production and use
of the spark in the cylinder, and also with a battery
connected with an entirely separate and distinct set

48 AUTOMOBILE IGNITION

of parts for ignition, this engine is said to have double
ignition. When double ignition is installed it is
possible to remove either the magneto system or the
battery system in its entirety and to run the engine
on the remaining system.

An engine may be equipped with a magneto which
is alone capable of generating a high tension current
ready to cause a spark, and in connection with this
magneto may be fitted a battery having a separate
induction coil used only with the battery current and
not when the magneto is in action. Except for the
coil all other parts of the ignition system, such as
the device for interrupting the flow of primary cur-
rent and the wiring leading to the cylinders, are
used either with the magneto or battery as a source
of current. Such a combination is called a trans-
former coil or a dual ignition system and by some
makers has been given the name of duplex ignition.

Many makers who call the combination just de-
scribed a duplex system also make a type given the
name of dual, but in the dual they provide one device
for interrupting the flow of current from the magneto
and a separate device for use with the battery current.

Some magnetos are so constructed that they con-
tain as a part of their armature winding an induc-
tion coil from which is secured high tension current
for the spark; these machines being called true high
tension magnetos. A true high tension magneto
may be used either for a single ignition system or
for a dual or duplex system, also as a part of a
double system.

Other magnetos generate only a low tension or low
voltage current and are used in connection with a
separate induction coil mounted at another point on

PRODUCTION OF ELECTRICITY 49

the car. These inachines go by the name of trans-
former coil magnetos or separate coil magnetos. A
transformer coil magneto is usually a dual machine
and the separate induction coil is used with the pri-
mary current from the magneto and also with the
primary current from a battery.

In case a transformer coil magneto with a battery,
which together form a dual system, are fitted to an
engine which also carries a completely separate and
distinct system of battery ignition independent of
the magneto system in every way, the combination
is called a triple ignition system.

We therefore have single, double, dual, duplex and
triple ignition composed of various combinations of
batteries, of true high tension magnetos and of trans-
former coil magnetos.

CHAPTER IV

PRODUCING THE SPARK
CONTACT BREAKERS

It has been explained in the preceding chapter
that the greatest voltage is secured from an induction
coil at the instant the primary circuit is broken. That
part of the ignition mechanism which causes this
break is called the contact breaker, circuit breaker
or interrupter and is a part with which the ignition
worker is apt to become well acquainted, both because
of the importance of this device and because of the
interesting methods that have been adopted in its
construction.

The principal parts of the breaker include two
contact pieces through which the primary circuit for
the induction coil passes while these contacts are
touching each other and which, when separated, pre-
vent a further flow of this primary current. In con-
nection with the contacts, or, as they are often called,
the contact points or simply the points, there is a
cam which causes their separation at the instant a
spark is desired in one of the engine cylinders. All
of the remaining parts of the breaker are for the
purpose of allowing the contacts and the cam to
operate properly.

Proper operation of the breaker requires that the
contact be quickly broken when it is time for the

PRODUCING THE SPARK

spark to occur, for a gradual separation of the points
would not produce a hot ignition spark. It is also
necessary that the contacts remain closed long enough
to allow the primary current through the coil to
thoroughly -magnetize the core, thus producing a
strong magnetic field which will act on the secondary

str/rc//

C0/1

B^rrs^y

Figure 13. — Breaker Location in Ignition Circuit.

coil winding. This does not necessarily mean that
the primary current should flow long enough to
completely saturate the core in all cases, because a
coil might be used which was built large enough to
allow a partial magnetization of the core to do the
work.

52 AUTOMOBILE IGNITION

The location of the breaker in the primary circuit
is shown in Figure 13. In this case the lower contact
is the one that mov^ and it is carried by a lever one
end of which is pivoted at P. The upper contact B
is stationary. With the switch closed it is possible

' for the current to flow from the battery and through
the primary winding of the ignition coil as soon as
the contacts come together. The circuit is then com-
plete through battery, coil and switch to the breaker
contacts ; then through these contacts as long as they
remain together and from the pivoted end of the lever
back to the battery. At the instant the contacts open,
a spark will be caused to pass in the engine cylinder.
Before another spark can be secured it is necessary
that the contacts close and again magnetize the coil.
Insulated or Grounded Primary. — As shown in
Figure 13 the entire circuit is carried through wires
and parts which are insulated. This plan, when found,
is called an insulated primary circuit. It has the
same characteristics and advantages that are found
in th6 two wire systems which were once the universal
practice in electric lighting and engine starting sys-
tems, among these being the fact that both sides of
the circuit from the battery would have to become
stripped of their insulation before an accidental short
circuit through other conductors would occur.

As generally found the primary circuit is com-
pleted through some of the metal parts of the engine
and framework of the car to which the ignition sys-

• tem is attached. In this case the system is called a
grounded primary type and the primary circuit is
shown in Figure 14. One of the battery terminals
is attached to the metal work, or grounded, and one
or the other of the contacts of the breaker is likewise

PRODUCING THE SPARK

in metallic contact with the remainder of the metal
parts so that the current is free to flow through this
uninsulated portion of the circuit because of the fact
that all metals form excellent conductors.

Breaker Contacts. — At the point of actual opening
in the primary circuit it is necessary to guard against

B/i£/tJ(£/r

M£TH e/lPl/Zi/O

Figure 14. — Grounded Primary Circuit.

the effects of heat due to the small arc or spark that
occurs at the instant of separation. This calls for
a material that will successfully resist a high degree
of temperature while at the same time conducting
the current with but slight resistance.

A metal very commonly employed for making the
contact points is platinum which will only melt at

54 AUTOMOBILE IGNITION

very high temperatures and which is but slightly
affected by the action of air. Because of the cost
of platinum very little is used except where abso-
lutely necessary and the contacts are therefore seldom
more than Ys inch thick and ^^ inch in diameter.
Oftentimes they are made much smaller than these
dimensions. The platinum is sometimes alloyed with
iridium, another rare and costly metal, which gives
the point greater hardness and resistance -to the ham-'
mering action than could be secured with pure plati-
num.

A large number of the breakers now being made are
equipped with contact points of tuijgsten, a metal
which combines resistance to heat with very good
wearing qualities. Alloys containing silver have also
been* used to some extent for making contact points
but the metals tungsten and platinum are almost
universally favored.

One of the contact points is stationary while the^.
other is movable. The stationary contact is securely
mounted on the body of the breaker and is the mem-
ber provided with means for changing the distance
between the points when separated, that is, the sta-
tionary contact is adjustable. The other contact is
moved to open and close the circuit and is not ad-
justable. The stationary contact may in some cases
be mounted on a spring to give certain flexibility as
the points come together and in such a construction
it is not, strictly speaking, stationary. Inasmuch as
one of the contacts is acted upon to cause the breaker '
action it may always be spoken of as the movable
contact, and the remaining one, however mounted, is
called stationary.

Contact Point Adjustment, — It is necessary that

PRODUCING THE SPARK 55

the contact points separate a certain distance from
each other when the circuit is opened by the breaker^
this distance usually being in the neighborhood of
eight to fifteen thousandths of an inch. With use
the surfaces of the contacts will wear or will become
uneven and require filing. In either case the reduc-
tion of thickness of the contact metal will cause the
opening to become greater than when the breaker waa
new and some means must be provided to again obtain
the correct distance.

In Figure 15 are shown methods of adjustment
which are in quite general use. In almost all case*
the adjustable contact is carried on the end of a
threaded screw and by turning this screw bne way
or the other the distance apart of the points when
separated may be made more or less, whichever may
be required.

At A, B and C are shown methods of securing a
screw which carries the adjustable contact with one
or more locking nuts. At A the screw passes through
the supporting body of metal and carries a locking
nut on the end opposite the contact while the screw
itself is hexagonal at one end to allow turning with
a small wrench. At B the screw passes into the
supporting metal and is prevented from turning by
a single locking nut. At C the screw carries a hexag-
onal head to which a wrench may be fitted and the
adjustment is maintained by two lock nuts, one on
either side of the support.

D, E and F show methods of clamping the screw
which carries the contact. At D the supporting metal
is slotted on one side and a clamping screw draws the
sides of the slot together, thus binding the threads
of the contact screw. The screw itself is turned by

AUTOMOBILE IGNITION

)

inserting- a small rod through holes in the enlarged
portion near the contact. The method shown at E
is somewhat similar to that at D with adjustment of
the contact screw provided for by the knurled head.
At F substantially the same result of clamping is

*^ y9

1 r

.1 fm///////

"Figure 15. — ^Methods of Adjusting" Breaker Contact Point

Gap.

secured, but in this case by means ^ of two locking
screws rather than with one.

At G the contact screw is provided with a number
of very thin washers underneath the head and be-
tween the head and the support. The adjustment is

PRODUCINa THE SPARK CT

made by taking the screw out of its support and
adding orsubstracting one or more of the thin wash-
ers, after which the screw is turned back into place
until secure. At H the adjustable contact point is
carried on one end of a slotted rod and through the
slot is a locking screw. The adjustment is made by
loosening the locking screw and pushing the rod one
way or the other on the screw, after which the adjust-
ment is made secure by tightening the lock. This
type of adjustment does not revolve or otherwise
change the position of the contacts in relation to
each other regardless of change in gap. With the
method shown at I the contact point is carried at
one end of a flat spring. An adjusting screw with
lock nut is provided which bears against this spring
and by turning the screw one way or the other the
spring is bent to bring the points closer together or
farther apart as may be desired.

BREAKER CAMS

The movable contact of the breaker is acted upon
by some form of cam w^ich is in turn operated by
power from the engine. The shaft from which the
cam is revolved is driven from the engine by positive
means such as gearing or chains because it is neces-
sary that the cam act to open the contacts at one
certain time in the engine cycle in order to secure
ignition at the end of the compression stroke.

In magneto construction, the breaker base, together
with the contact carrying parts, may revolVe as a
unit; the cams then being mounted in the housing
and remaining stationary. This is the reverse of the
method generally used with battery systema. Tba.

58 AUTOMOBILrB IGNITION

foUowing matter in this chapter refers particularly
to battery ignition.

In the four cycle engine each cylinder fires once
for each two revolutions of the crank shaft. A single
cylinder engine would therefore require one spark,
which would call for one separation of the breaker
contacts every second revolution of the crankshaft.
A two cylinder engine would require twice as many
sparks, or one for each revolution of the crank shaft.
Four cylinders call for two sparks each crankshaft
revolution, six cylinders for three sparks, eight cylin-
ders for four sparks and twelve cylinders for six
45parks each revolution. In other words, an engine
will require a number of sparks during each crank-
shaft revolution which is equal to the number of
cylindens divided by two and each spark calls for one
separation of the breaker contacts.

The breaker shaft ot battery ignition systems oper-
ates in practically all cases at the same speed in
relation to the engine crank shaft as does the shaft
w^hich opens and closes the valves for the various
cylinders, this being one-half as ^f ast as the crank
shaft. The cam which opens the breaker contacts
w^ill therefore require as many lobes or points which
cause the contacts to separate as there are cylinders
of the engine. This last statement holds true in all
cases where the breaker is provided with but one
set of contacts in operation at one time. Very high
speed engines of six, eight and twelve cylinders are
sometimes provided with two sets of contacts opening
alternately which of course cuts the number of cam
lobes in half.

In Figure 16 are shown forms of breaker cams, all
of which are found in the installations on various cars

PRODUCING THE SPARK

and of various makes of ignition equipment. At A
are shown very simple iorm^ in shapes suitable for
firing four cylinders (square), six cylinders (hex-
agonal) or eight cylinders (octagonal). With rotation
of such a cam the contacts will be separated each

zzzzBk

^omnanzzzrnL

Fiffure 16. — Construction of Breaker Cams.

time one of the comers strikes the projection on the
arm or lever which carries the movable contact point.
In order to secure the desired opening between the
contacts, but still without causing them to remain
together as long as would be the case in the forcas

60 AUTOMOBILE IGNITION

shown at A, the corners may be rounded as shown
at B. This form keeps the contacts apart while the
projection on the lever rides over the rounded por-
tion und allows them to close only while the flats of
the cam pass under the lever. The longer flats shown
at A a]low a longer time for closing of the contacts
which of course calls for a greater expenditure of
current due to the longer time of contact.

The three forms of cams shown at C, D and B
are all modifications of a circle. At C the lobes are
formed on the outside of the circle while at D, an
eight cylinder type, the lobes are formed by cutting
small arcs of circles into the circumference of the cam.
At E is shown another four cylinder type.

At F is shown a cam which closes the contacts only
during the very short length of time during which the
contact carrying lever rides over the outer end of one
of the small points formed around the cam body. The
shape of this cam, in which one side of the point rises
gradually, while the other drops very abruptly, causes
a quick break as the. contact lever drops off the top of
the point.

The cam used with Atwater-Kent svstems of one
type is shown at G. This form consists of a series of
notches,, one for each cylinder, cut into the circum-
ference of a circle. A hooked arm catclies in the notch
as the cam turns and the arm is drawn in the same
direction that the cam rotates. With continued turn-
ing the hook of the arm slips out of the notch and the
quick return opens the contacts. This type is fully
described in Chapter Seven.

In the early types of Westinghouse apparatus no
separate cam was provided but the contacts were
caused to separate when one of the centrifugal gov-

PRODUCING THE SPARK 61

emor weights struck against a spring arm which
released the lever to which the movable contact was
attached. This form of apparatus is illustrated in
Figure 60.

In most cases the breaker cam is solidly fastened
to its shaft and in order to change its relation to the
engine parts the relative position of the driving gears
or chains must be altered. One exception to this prac-
tice occurs in Delco equipment wherein the cam is
secured to its shaft by means of a screw with a tapered
head which threads into the shaft and holds the cam
in position by the tightly drawn taper fitting.

BREAKER ARMS AND LEVERS

The movable contact of the breaker is carried by
a hinged or pivoted arm or lever which allows the
necessary opening to take place between the contacts
while in operation. Inasmuch as this arm or lever,
with its attached contact, must move once for each
spark produced it must be capable of performing
these movements with exceeding rapidity. The lever
is Tield in one position, either with the contacts open
or closed, by a spring and is then operated by one
of the forms of cams already described. Lightness
is generally desirable in a breaker arm so that the
mechanical lag may be reduced as much as possible.

One end of the breaker arm is generally supported
by a hinge of some kind. In most cases this hinge is
formed by a pivot carried by the breaker body and
over which fits a hole in one end of the arm. In many
constructions this hole carries a bushing or lining of
fibre so that the two metal surfaces are kept apart and
the danger 6t binding is reduced. A hinge may also

AUTOMOBIL»E IGNITION

be formed by attaching a thin flat spring to one end
of the arm and supporting the other end of this spring
on part of the breaker base, the spring allowing suffi- .
cient movement of the arm for opening and closing'
of the contacts.

Breaker arms may be straight or nearly straight
from end to end. They may also be curved or L
shaped. The form of arm has but little to do with
its action but is adopted to accommodate the shape
of the whole breaker mechanism, whether long or
circular.

The contact point may be carried on the end of
the lever farthest from the hinge, in which case the

Figrure 17. — ^Action of Breaker Cam on One Piece Arm.

cam acts on the lever at or near its center; or the
contact may be near the center of the lever and the
cam may then act on the lever's end. The lever is
fitted with some form of bumper against which the
cam strikes, this bumper being made from fibre or
from the metal itself. The fibre bumper may be in
the form of a block of suitable shape or may be cir-
cular. A circular bumper is sometimes capable of
being turned around its axis so that new surfaces are
presented to the cam as old ones become worn.

A number of breaker constructions make use of
contact levers formed of two pieces of spring steel,

PRODUCING THE SPARK 63

one of which carries the contact point while the other
is directly acted upon by the cam. This form of lever
is found in those systems which provide that the cam
close a pair of contacts which are normally open. The

Figure 18. — ^Action of Two Piece Breaker Arm.

reason for employing a double spring arm may be
understood by reference to Figures 17 and 18. In
position A of Figure 17 the contacts are open and the
spring arm carrying the movable contact is straight.
With the contacts closed because of cam action, as'
shown at B, the spring lever has been bent. Such
action could not continue as the bending would soon
destroy the lever's usefulness.

In Figure 18 is shown a form of double spring arm
which obviates the diflSculty that would be found with
but a single spring. In the open position at A the

Figure 19. — Two Piece Breaker Arms. Left: Westinghouse.

Right: Etelco.

hooked end of the spring which carries the bumper is
holding the contacts apart. At B the cam is shown
in position to close the contacts, the hooked member
having moved the contact carrying spring until the

AUTOMOBILE IGNITION

contacts are together, then continued its movement
until the point of the cam has passed, but without
further movement of the contacts themselveg.

Double levers which operate in much the same way
as the form just described are shown in Figure 19,
that at A having been used with some of the earlier
Westinghouse installations and that at B being a form
used by Delco. Types of intermediate arms or strik-

Figrure 20.— Breaker Using Intermediate Striker (Philbrln).

ers which act between the cam or cam operated lever
and the arm' carrying the movable contact are shown
in Figures 20 and 74. The form having three levers
in Figure 74 is an Atwater Kent characteristic and
the form in Figure 20, which utilizes a small plunger
for carrying the contact, being found on Philbrin
systems.

It has been found that the speed of some multi-
cylinder engines may call for a number of sparks
greater than can readily be furnished by a single

PRODUCING THE SPARK

breaker because of the fact that the contacts cannot
remain together for a long enough time to insure mag-
netization of the induction coil. To obviate this diflB-
eulty, breakers have been made with two levers and
two sets of contact points. A form of Delco equip-
ment having two levers operating from different points
around the same three lobed cam and carried in a
plane with each other is shown in Figure 21. A

Figure 21. — ^Double Arm. Single Cam Breaker for High Speed

Engines (Delco).

Remy design for high speed engines provides two
contact arms both operated by one cam and carried
one above the other. In this connection it may be
noted that a twelve cylinder engine running at 1800
revolutions per minute calls for one hundred and
forty sparks during every second of operation, or
8,400 during each minute.

In Figure 22 is shown the contact point arrange-
ment used with older types of Westinghouse equip-

AUTOMOBILE IGNITION

ment. This construction hangs two movable contacts
from a single bar, this bar being then operated by the
lever against which the cam acts. The two sets of
contact points are in a series with each other, current
entering the breaker through one set, passing through
the contacts and the supporting bar, then leaving the
breaker through the remaining set of contacts.

Figure 22.^Double Contact Breaker (Westinghouse).

THE CONDENSER

If a battery, coil and breaker be connected in a
circuit as shown in Figure 23 it will be found that
a powerful and hot spark will be produced at the
breaker contacts as they separate. This spark has
sufficient heat to quickly destroy the contact points
and is caused by an action in the coil which is called
**self induction."

It has been explained that the change of magnetism
in the core of the coil which takes place upon break-
ing the primary current causes a flow of current in
the secondary winding of the coil and this same change

PRODUCING THE SPARK

of magnetism produces a flow of current in the pri-
mary winding as well. This induced flow caused by
breaking the current at the points is of much greater
voltage than the primary current itself and tends to-
continue to flow between the contacts as they open,
thus causing an arc or hot spark.

A device called a condenser is incorporated in the
ignition apparatus for the purpose of collecting this
induced current, preventing its causing a destructive-
arc at the contacts and also allowing the power of the
induced current to be returned to the coil in such a

c^/i

Figure 23. — ^Primary Igmition Circuit Without Condenser.

way that the change of magnetism affecting the sec-
ondary winding is greatly increased and the resulting
current in the secondary circuit is raised in voltage
to produce a spark much hotter than would otherwise
be secured.

The condenser consists, in the form usually em-
ployed, of a number of strips of tin foil separated by
insulators such as oiled or paraflned paper or cloth.
Mica also is used in some cases as the insulator.
Alternate strips of the tin foil are attached to each
other so that one half the total number of strips con-

•68 AUTOMOBILE IGNITION

nects with one tQpninal of the condenser while the
remaining half connects with the other, terminal. This
arranagement provides a large surface of an electrical
-conductor (tin foil) separated by very thin layers of
insulating material, which is, in this case, called the
■dielectric. A condenser has the ability to hold a cer-
tain amount of electrical energy which is stored on
the conductor sheets when the condenser terminals are
subjected to a differ ence of voltage, as would be the
•case when connected in the primary circuit across the
breaker contacts. The position of a condenser, con-
nected between the breaker contacts, is shown in Fig-
xire 24.

As the breaker contacts open, the magnetism dies
out of the core of the coil and this change in mag-
netism induces a current in both primary and sec-
ondary windings. Whereas the voltage from the bat-
tery and dynamo may be between six and eight, the
induced voltage in the primary winding of the coil
may rise to one hundred or one hundred and twenty-
five volts. In place of expending itself in forming
an arc between the breaker contacts, this high voltage
charges the condenser and the condenser then imme-
diately discharges itself back through the coil, but in
a direction the reverse of that taken by the battery
current. This powerful reverse discharge from the
condenser quickly demagnetizes the core of the coil
and remagnetizes it in the reverse direction with the
result that the total change of magnetism, from that
first caused by the battery current to that of reverse
polarity caused by the condenser's discharge, is very
great and a very high voltage is produced in the sec-
ondary winding with a resulting hot spark at the
plugs in the cylinders.

PRODUCING the: SPARK

6»

Should the condenser fail because of becoming
disconnected the result will be severe sparking at
the breaker contacts and a weak spark at the plugs.
Breaking down of the dielectric or insulation between,
the leaves of the condenser will short circuit th^ con-
tacts and weaken or prevent the spark at the plugs.

COAfOS^Sf/f

Figure 24. — ^Lrocation of Condenser in Primary Circuit.

•

The condenser may be located in the breaker hous-
ing very close to the contacts themselves, or in the coil
housing or as a separate unit in its own housing at
some point between the coil and breaker. It is thought
best to carry the condenser as close as possible to either
coil or contacts, so that wiring between these parts
is greatly reduced or in some cases practically elimi-
nated. The best practice is undoubtedly to have the^
coil, the breaker and the condenser as close to each

•70 ; AUTOMOBILE IGNITION

other as possible so that tho primary wiriAg, except
that to the battery and switch, is reduced to a mini-
muni. In this way the flow of current between coil
and condenser finds but very little resistance and the
same is true of the flow past the condenser to the
breaker contacts.

THE DISTRIBUTOB

The distributor receives the flow of secondary or
high tension current from the fine wire winding of
the spark coil and directs this flow of current into
the wire leading to the spark plug in the cylinder
which is then ready to fire, that is, to the cylinder
whose piston is at the uppet end of its compression
jstroke and ready to descend on the power stroke.

The distributor consists of an insulating cap or
head in which ai*e secured the terminals to which
spark plug wires attach and in most cases in which
the terminal carrying the wire from the spark coil is
also mounted. Inside of the cap is a revolving mem-
ber called the rotor which receives the high tension
current from the coil, and, by moving from point to
point around the cap, carries this current to seg-
ments or pins which ate in electrical connection with
the several spark plug wires.

The electrical connections for the distributor are
shown in Figure 25. From the secondary winding of
i;he coil a flow of current takes place each time the
breaker contacts separate and this flow passes through
i;he line C to the rotor of the distributor. As each
flow of current is received, the rotor is in position to
-carry the current to one of the terminals and from
Ihis terminal the current is carried to a spark plug.

PRODUCING THE SPARK

Jumping the gap in the plug, the current produces
the spark which ignites the mixture and then con-
tinues through the metal shell of the plug to the
ground or metal of the engine and car. The other end
of the secondary winding of the coil is also grounded
to the metal work so that the high tension current
passes back to the coil winding and completes the high

coa

SMM . PlffO

FifiTure 25.— Location of Distributor in High Tension Circuit.

tension circuit. By the time the breaker contacts
again open, the distributor rotor is in position to send
the current to the plug in the cylinder then ready to
fire and the action continues in this way.

Because of the necessity of revolving the rotor to
keep time with the action of the breaker, the distrib-
utor of battery systems is generally carried directly
above the breaker housing and the rotor is mounted

AUTOMOBILB IGNITION

on the upper end of the shaft which carries the
breaker cam. The rotor ie so placed in relation to
the lobes on the cam that each time the contacts
separate, the rotor is in position to send the high
tension current to one of the plugs.

In some forms of battery ignition apparatus and
generally with magnetos the distributor is mounted
above the breaker but with both breaker and distrib-
utor- rotating in the same plane as shown in FigT;ire
26, Iii this type of equipment the breaker cam has

Figrure 26. — (Breaker and Distributor of Magneto Tjrpe.

only half the number of lobes as there are cylinders
to be fired and the distributor rotates at one half the
breaker speed. The driving connection between the
two parts is secured by a gear carrying the distributor
rotor meshing with a pinion half the size of this gear
and mounted on the breaker shaft.

Two distinct types of distributor construction are

in use. One type, called the wipe contact, provides

carbon or metal brushes in the distributor rotor or

the cap, or in both rotor and cap, which complete the

PRODUCING THE SPARK 73

connection for the high tension current. The other
type, called a jump spark distributor, leaves a minute
air gap between the current carrying member of the
rotor and the connection for the spark plug cable
terminal, the secondary current jumping across this
air'gap for each discharge of high tension current.

Jump Spark Distributor, — The jump spark dis-
tributor includes a rotor having a metallic current
carrying member mounted on the body of the rotor
and with its outer end traveling very close to a series

Figure 27. — Rotor and Segment Pins of Jump Spark

Distributor.

of pins set into the cap or head of the distributor as
shown in Figures 27 and 75. One pin is provided for
each spark plug cable arid the outer end of the rotor
metal is made wide enough so that, regardless of the
degree of advance or retard, within practical limits,
the rotor is always opposite one of the pins during
the discharge of high tension current to the plug.
The center of the rotor, at \?Yv\e\i ^cIwvX. "Ocsfc ^^izt^'sciv.'^s-
received from the coil VTindm^, xas:^ T^e««^ '^^ ^^^^^'

AUTOMaBIL.E IGNITION

rent thrqugh another pin and across a gap similar to .
those leading to the spark plug lines, through a spring
contact bearing against a metal segment or pin or
through a carbon or metal brush carried in -the cap
or by the rotor. The positive spring or brush con-
tact for the coil terminal is generally favored in pref-
erence to the jump spark type at this point.
The gap between the outer end of the rotor and

Figure 28.— Rotor and Brushes of Wipe Contact Distributor.

the spark plug pins is generally made from five to
eight thousandths of an inch, or about one fifth the
gap used between the points of the spark plug. This
gap should be sufficient to prevent either rubbing
contact or any excess space at this point. One pur-
pose of using the jump spark type rather than the
wijDe contact form is to do away with the rubbing
action necessary in the wipe coivt8LC\. \)iw\. Vt Ve. ^'^'^

PRODUCING THE SPARK 7^

intended to cause any more resistance than is abso-
lutely necessary.

Wipe Contact Distrihutor. — The wipe contact dis-
tributor, shown in Figure 28, introduces no additional
air gaps into the secondary circuit but does make use-
of two sliding contacts, one as the current enters the-
distributor from the coil and the other as the current,
leaves to the spark plug lines. While metal brushes,
solid and of button shape, have been used in complet-
ing these sliding or wipe contacts, the general practice
is to use cylindrical or rectangular pieces of carbon
held in contact with metallic pieces by means of small
coiled springs. Brushes made from fine mesh copper
wire screen wound into cylindrical form have also been
used from time to time.

In the form of wipe contact distributor shown, all
of the brushes are carried in the cap or head. There^
is then one central brush connecting with the lead
from the coil and resting on the center part of the
rotor metal. Around the edge of the cap are brushes^
equal in number to the number of cylinders of the^
engine. These brushes bear on the outer end of the
rotor as it revolves. The rotor itself consists of an
insulating plate, perfectly flat in the portion traveling
under the spark plug brushes and with a metal piece
set flush with the insulating plate. This metal piece
makes contact with the coil brush at the center of the
rotor and passes successively under each of the spark
plug brushes during rotation.

A generally used form of wipe contact distributor,
as shown in Figure 29, carries two brushes in the
rotor, one of these brushes being always in contact
with a segment in the cap which coiAiAe.<it% ^\5(!^ ^3sn&
coil terminal while the otlieT \iT\x^\^ ^\.\^^^^^^^^^^

aotouobile; ignition

end of the rotor body and makes contact saeeesBively
with segments set £u8h with the insulating material

■of the eap and which conjiect with the wires leading
to the spark plugs for the several cylinders.

In other constnictiwis the rotor carries one brush
at its revolving end, this brush making successive con-
tact with segments for the spark plug lines, while the
■coil terminal brush is mounted in the cap and beara
■on a metal piece in the center of the rotor with elec-

Wlpe Contact Distributor Construction.

trical connection between this center piece and the
holder for the revolving brush. Some models of
Westinghouse equipment carry two brushes, one above
the other, in the revolving end of the rotor. In this
case the high tension from the coil is lead to a ring
■around which the lower brush travels while the upper
brush moves around a track in the cap which includes
segments for the spark plug lines.

CHAPTER V

THE IGNITION CIRCUIT

CLOSED AND OPEN CIRCUIT SYSTEMS

•

An ignition breaker may be so designed that the
contact points are normally held closed by a spring
and are opened by the action of the cam, or it may
be so built that the contacts are held open by the
spring and are closed by the cam. The first method^
with the contacts normally closed, is called a closed
circuit system, while the second, with the contacts
held apart until pressed together by cam action, is
called the open circuit system. Delco, Atwater Kent
and Westinghouse systems have been built in both
types. Remy, Connecticut, Bosch and Splitdorf equip-
ment has favored the closed circuit plan, while Pitts-
field, Philbrin and Rhoades form examples of open
circuit systems.

The two principles of construction, one closed cir-
cuit and the other open circuit are shown in Figure
30. At A is shown the construction of a closed cir-
cuit type in which the contacts P are held closed by
the spring S until the cam D strikes the bumper on
the arm E which carries one of the contact points.
At this instant the contacts separate and the spark* is.
produced. The contacts remain apart until the lobe
of the cam passes from under the bumper. The pri-
mary current fiows through the eoil dvwcvc^% ^3ssfc ^kss5>s^

AUTOMOBILE IGNITION

between the instant at which the cam allows the spring
to close the contacts and the instant at which they
are once more separated.

At B is shown the principle used with open circuit
systems. The contacts P are held apart by the spring
-arm S until the cam D jstrikes the bumper. As the
^rm S is moved, arm E travels toward the stationary
<3ontact, until at some point which is determined by
the initial gap between the contacts, they come to-
gether. At this instant the primary current starts to
flow through the coil winding and continues to do so
•during further rotation of the cam. This continued

figure 30. — Breaker Construction. A: Closed Circuit Type.

B: Open Circuit Type.

movement of the cam carries arm S still closer to the
stationary contact, but with the points once closed
arm E no longer moves because the hooked end of S
releases this contact carrying member to avoid undue
pressure on the points themselves. As the lobe of the
<3am passes from under the bumper the spring arm S
<;atches arm E by means of the hooked end and pulls
the contacts apart. As they separate, the current stops
flowing through the coil and the spark takes place.
It will be noted that in the closed circuit type shown
^t A the spark takes place when the forward side of
^2ie cam lobe strikes the bumper, ^YoV^ m \Xi^ o^^xi

THE IGNITION CIRCUIT 79

circuit type shown at B the spark passes when the
rear side of the cam lobe leaves the bumper.

In either of the types just explained it will be seen
that with the cam lobe in the position as shown at
A, or with the lobe directly under the bumper in the
mechanism shown at B, primary current will flow
through the circuit whenever the ignition switch is
closed and with the engine idle so that the cam remains
in the position mentioned in either case. It will also
be noted that the time during which the contacts
remain together will, of course, be longer with the
engine running slowly than with it running fast.
With the engine running slowly the cam is revolving
slowly and it takes a certain definite interval for the
lobe of the cam to act either in opening or closing the
contacts. This same interval, determined by the en-
gine speed, determines the absolute length of time
during which the contacts remain closed and during
which the core of the coil is being magnetized by the
primary current. With increased speed of the engine
the cam is traveling faster and the time interval, dur-
ing which the contacts remain closed and allow cur-
rent to flow through the coil, is correspondingly
reduced.

With a cam built for a four cylinder engine and so
designed that the time the contacts are open is just
equal to the time between openings, and during which
-they are closed, the primary current would flow
through the coil during thirty thousandths of a second
at an engine speed of five hundred revolutions a min-
ute. At an engine speed twice as fast, or one thou-
sand revolutions a minute the coil would receive cur-
rent during fifteen thousandths of a second and at
fiffeen hundred revolutioiva a TCvmxjiV^ \wc \sxv *Csx<s^-

AUTOMOBILE IGNITION

sandths of a second ; the time in fractionis of a second
during which the core of the coil must be magnetized
becoming less in direct ratio to the increase of engine
speed. As a result of this condition in operation the
coil windings must be so proportioned that the mini-
mum possible time during which the contacts are
closed, that is, at the highest attainable engine speeds,
will be sufficient to build up the magnetism in the
core of the coil to a point such that breaking of the

ffC

SP££a

Figure 31. — Current Consumption of Closed Circuit System

(Atwater Kent).

primary circuit wiU cause a reaction sufficiently
powerful to produce a spark having heat enough to
ignite the mixture.

It is also true that a strong spark is desirable when

starting an engine from rest because of the lower com-

pression and also because of the fact that the gases

THE IGNITION CIRCUIT 81

are cold and tend to condense rapidly on the cylinder
walls of the engine. The breaker types just described
deliver their hottest sparks when the engine is'being^
cranked because it is at this time that the coil is
energized during the longest absolute time, while after
the engine starts and with continued increase in
crank- and cam-shaft speed the strength of the spark
becomes progressively weaker.

The current consumption of the Atwater Kent
closed circuit system is shown in Figure 31 for engine
speeds from zero up to four thousand a minute.
With the engine idle (zero revolutions) the current
consumption is very high because there is a free flow
from the battery through the primary circuit, hin-
dered only by the normal resistance of the circuit.
After the engine starts, the current consumption falls
lower and lower with increase of engine speed because
of the lessening time interval during which the breaker
contacts are closed. With this decrease of current
consumption there is a corresponding decrease in the
heat or power of the spark delivered through the
plugs.

The design of breaker shown in Figure 32 is of
the true open circuit type in which the contacts are
always open with the engine idle regardless of the
cam position and in which the time duration of the
contact between the points i^ constant for any and all
engine speeds. The particular design shown is one
of the first Atwater Kent constructions and well illus-
trates the principle involved.

The cam D is in this case .formed with a series of
notches around its circumference. As the cam re-
volves, it draws the latched arm T ahead with it as
the latch catches in one of t\\^ c^xaxLoXO^^^. ^sX\5st s:5si&

82 AUTOMOBILE IGNITION

latch has been drawn a certain distance ahead, the
notch of the cam rides away from the hooked end and
the latch, being thus released, is quickly drawn back,
ty the tension of the small coiled spring S. In its
backward travel the latch strikes a Bmall extension
on the compound breaker arm E just as the end of
the latch passes over the high part of the cam which
is between two notches. The contacts P are momen-

^~iinmi^

tarily thrown together at this time and the primary
circuit is completed. The arm E is immediately re-
leased and the contacts again open. In this case the
length of time during which the contacts are closed in
no wise depends on the speed of rotation of the cam
■or of the engine, but is governed entirely by the speed
with which the latch is returned after its release by
the coiled spring and this speed is the same regardless
<of all other conditions.
With aacb a type of true open circMiit bi:ftakCT the

THE IGNITION CIRCUIT

coil windings are so proportioned that the necessary
magnetization is accomplished during the time that the
contacts are together and with this proportion right
for one speed of the engine it is, of course, right for
all other speeds and the value of the secondary spark
is always the same, in starting and at all running
speeds.

•

Jic

Jdc

Figure 33. — Current Consumption of True Open Circuit Sys-
tem (Atwater Kent).

A true open circuit system uses more and more
current as the engine speed increases due to the
greater number of times that the circuit is closed, all
of these times being of the same duration in fractions
of a second. The current consumption of one of the
new Atwater Kent open circuit systems is shown for
various engine speeds in Figvxx^ "Sli. W ^w^\i^ \ss:Nfc^

AU^rOMOBILE IGNITION

that the current consumption is very much less at low
ranges of speed than with Ihe closed circuit type and
in no case reaches as great consumption as the closed
circuit type at any engine speeds in ordinary use.

Another example of the true open circuit type of
breaker is found in the Rhoades system, the construc-
tion of which is shown iu Figure 34. The cam in the
Rhoades breaker carries a number of projecting points
and these revolve past an extension on the spring arm
T, pressing this arm back. As soon as the point of

Figure 34. — Breaker of True Open Circuit Type (Rhoades),

the cam passes from under the extension on the spring
arm the arm itself flies back and its free end strikes
the outer end of the compound contact-carrying arm
E. The force of the blow thus delivered causes the
contacts P to be momentarily thrown together and the
primary circuit is completed. At all times except
when the arm E is struck by the spring actuated blow
from arm T, the contacts are held apart and the cir»
cult 18 open reg-ardless of the position, oi t\vei smtftlu

THE IGNITION CIRCUIT 85

RESISTANCE UNIT

In the foregoing explanation of open and closed
circuit systems it was shown that it is possible in the
closed circuit and in the usual open circuit construc-
tion for the primary current to flow through the cir-
cuit with the switch closed and the engine idle. Such
a flow of current would discharge the battery rapidly,
would cause damaging burning of the metal compos-
ing the breaker contact points and would so heat the
primary winding of the spark coil that this unit
would eventually be rendered useless.

It was also explained that the current consumption
with these types of breakers is greater at low engine
speeds than at higher speeds and that the consump-
tion at high speeds is suflBcient to cause the coil to give
a proper ignition spark.

For all of these reasons it is desirable that the flow
of primary current be restricted at low engine speeds
and that it be stopped or nearly stopped should the
ignition switch remain closed with the engine idle.
This object is accomplished by inserting in the pri-
mary circuit, usually near the coil or the breaker, a
small length of wire arranged in a coil, this wire hav-
ing the property of becoming heated with any great
flow of current and when heated having the further
property of greatly increasing its electical resistance
so that the flow of current through it is reduced to a
low value.

The resistance unit is made from iron wire because
this metal has the electrical characteristics mentioned,
• that is, increase of resistance after a certain critical
degree of heat has been passed. TYv^ XL^^^^^easrs V:^^^^.
ot wire is formed into a smaW eoW axi^ wssoaScj ^^ivR5^

80 AUTOMOBILE IGNITION

around a heat proof spool which is then carried in a
mounting open to air circulation. The heat may be
radiated and the wire still protected against water and
dirt falling directly into the coil. A sufficient length
of wire is used to make the resistance of 'the unit con-
siderably in excess of the resistance of the primary
winding of the coil. This device is commonly found
with Delco and Remy and Westinghouse equipment.

With a coil designed for battery ignition and to be
used with such a resistance unit in circuit, the pri-
mary current at low speeds would be several times its
normal value were the resistance unit taken out of
the circuit. The primary current in such a circuit is
limited by the combined resistance of the coil winding
and the resistance unit, together with the impedence
of the coil which is the choking effect opposing any
pulsating current magnetizing an iron core. This
impedence increases as the speed of the pulsations, due
to the opening and closing of the breaker contacts,
increases. At low speeds, due to the greater fl©w of
primary current causing heating of the wire, there
will be a consequent^ increase in its electrical resist-
ance. ^

Should the resistance unit become short circuited
damaging results to the breaker contacts, battery and
coil will take place; while with the resistance unit
broken or out of the circuit for any reason, there can
be no flow of primary current and no spark wiU be
generated.

SAFETY SPARK GAP

In order to pass across the gap in the spark plugs

snd thereby produce a spark in the mixture, the high

tension or secondary current "haa a px^'svxt^ <il tcv^xy-^

THE IGNITION CIRCUIT 87

thousand volts. Should a spark plug wire break or
should any other interruption tal^e place in the nor-
mal path of the high tension current from the cqil to
the distributor, thence to the plugs and through the
ground back to the coil, this great voltage tends to
force the escape of the current through the easiest
available path which may be through the insulation
of the coil windings themselves or through the insula-
tioiT of some of the other units in the circuit.

The voltage required to send the high tension cur-
rent across the gap in the plugs and through the com-
pressed mixture of fuel gas and air is about the same
as that voltage which will send the current across a
gap of one quarter of an inch in the outside air. The
insulation of the coil windings and other high tension
current carrying parts is strong enough to resist a
current which would jump a gap of about one half
inch in the air. The insulation resistance, being thus
greater than the resistance across the spark plug gap,
holds the secondary current to its proper path and
forces it across the plug gap as the easiest place to
escape to the metal or ground connection of the car.

Under most conditions of operation the proportion-
ing of the battery voltage and the windings of the
coil is sufficient to generate a secondary voltage high
enough to send the current right through the insula-
tion of the coil windings or spark plug cables were it
not easier for this current to pass through the plug.
It will be seen that a break in the line to the plugs
will very likely result in serious damage unless some
other path be provided through which the high volt-
age current may escape. This safety path is provided
in the form called a safety spatk ^'Xi^.

A safety spark gap coiisve\E ol \.^^ m^\s^ ^^xxis».

88 AUTOMOBILE IGNITION

separated in most cases by a space of about three
eighths of an inch, as shown on the coil in Figure 35.
One of these points is in electrical connection with
the secondary circuit after it leaves the coil winding,
while the other point is in connection with the metal
or ground. Inasmuch as the gap in the spark plug
has a resistance equal to about one quarter inch of
open air, while the opening of the safety spark gap '
is three eighths of an inch, the high tension current
will take the path of lower resistance through the plug

Figure 35. — Construction of Ignition Coll (Connecticut).

and will produce an ignition spark rather than flowing
away at the safety gap. Should, however, the gap at
the plug become so great as to introduce extraordi-
nary resistance or should there be a break in the cir-
cuit so that the current could not reach the plug, thea
the secondary current will find the next easiest path
/to gronnd through the safety spark gap whose resist-
•ajiee, equal to three eighths of an ine^ ot b;\t,Ss sSSi

THE IGNITION CIRCUIT 8^

less than the resistance of the insulation of the coil
and ignition parts.

The safety spark gap may be carried on the body
of the coil so that one of its points is connected
directly with the outlet of the secondary winding, or
it may be mounted or built into the distributor mech-
anism in which, case it protects all of the secondary
circuit except that part between coil and distributor^
The location of the safety gaps is mentioned in Chap-
ters Seven, Eleven, Twelve and Thirteen. Passage of
a spark at this gap always indicates that there is
excessive resistance, such as an incorrect spark plu^
gap, or a break somewhere in the high tension circuit
and this break or resistance should be at once located
and corrected.

IGNITION COILS

The mechanical construction of a coil is shown by
Figure 35. The core is composed of a bundle of iron
wire surrounded by an insulating covering. On the
outside of this covering is placed the primary winding-
which consists of a few turns of comparatively heavy
gauge wire. A second insulating covering is then ap-
plied and the fine wire secondary winding is placed
over it. In the construction shown, the condenser is.
carried within the coil case and the safety spark gap
is carried on the outside of the case. The parts have
nothing to do with the coil proper but are thus posi-
tioned for convenience.

In Figure 36 is shown, in a general way, the con-
struction and internal wiring of a typical ignition coil
(Delco.) This coil unit includes within its housing-
the condenser and on tTie owXsE^^^ei ^1 \X\ft ^-^^Rfc^ ^isX *^^5s^

left end of the illustration, is shown a resistance onit
which acts to prevent excessive flow of current through

the coil winding.

Figure 37 shows the internal winding of a coil and
the connections between this unit and the other parts
of a complete battery ignition system (Connecticut),
The coil shown is the same as that illustrated in Fig-
ure 35, but in this case the mechanical details are re-
placed by diagrams of the electrical circuits. Tracing
the current from the battery it will be found to pass
to the reversing switch, then through the primary
winding of the coil and to the stationary contact of

firffwtiWmmc. ■

Comi'OiJt.'-'^
Figure 36, — Internal Connectlone

r Ignition Coil (Delco).

the breaker. The movable breaker contact is con-
nected with the remaining side of the reversing switch
and from there the cuirent flow is grounded. The
condenser, carried in the coil, is electrically connected
between the breaker contacts as shown.

SPARE PLUGS

The spark plug is a device designed to carry the
high tension current into the combustion space of the
engine and there to allow the current to form an arc

THE IGNITION CIHCUIT

or spark between two points separated by a definite
gap, the heat of this spark eausing ignition of the
fuel mixture to take place. The spark plug must

AUTOMOBILE IGNITION

operate under the difficult conditions of extreme varia-
tions in temperature and pressure while at the same
time preventing the improper escape of an electric
current of thousands of volts pressure. While this
unit is small and generally of simple construction it
is among the most important and highly developed in
the whole ignition system.

In its simplest form the spark plug consists of a
shell threaded on its outside sul'face so that it screws
into some part of the combustion space wall, and
inside of this shell an insulating bushing through
which passes a conductor called the central electrode

iJifsi/i/fToa

'SHELL
Figure 38. — Principal Parts of a Spark Plug.

and through which the secondary current enters the
combustion space. These parts of the plug are shown
in Figure 38. The design of the .shells of various
makes and types of plugs has been practically stand-
ardized and but little variation is found in the for-
mation of the central electrodes. In the insulator
and in the form of the ground electrode or lower end
of the shell, designers have exercised their ingenuity
to the fullest extent with the result that some remark-
able constructions have been evolved.

ZnsieZafor.— ^Materials used in the building of insu-
lators for spark plugs include porcelain, soapstone,

THE IGNITION CIRCUIT 93

lava, mica and artificial stone. All of these mate-
rials have the common characteristics of resisting
the passage of electric current and in varying degrees
of resisting the action of heat and the effects of
burned and partially burned oil and fuel mixtures.
The two greatest foes of thie spark plug are deposits of
oil or carbon and accidental damage to the insula-
tors and it has been with an idea of overcoming these
obstacles to perfect working that the various depar-
tures in design have been brought into use.

Porcelain for use as an insulator is of very fine
close grain and is finished with a coating to give a
high gloss on which it is difficult for carbon deposits
to accumulate and through which carbon and oil will
not penetrate as long as the glaze is unbroken. This
porcelain is made to successfully withstand very high
^ degrees of heat and also to withstand sudden changes
from heat to comparative cold. Porcelain has the two
inherent disadvantages of liability to fracture from
mechanical damage and of a coefficient or rate of
expansion that differs considerably from the rate of
expansion of the metal parts in which it is held. This
difference in expansion gives rise to severe mechani-
cal strains against which it is necessary to provide
means for relief.

Mica insulators are formed from very thin sheets
of this mineral, either wrapped around the central
electrode to form a jacket or else cut into discs or
washers which are placed one on the other with the
central electrode passing through an opening in their
center until a sufficient number have been assembled
to form an insulator of the desired length. In some
cases a combination of the wrapped sheet with the
washers is used. After the insulating core has been

AUTOMOBILE IGNITION

built up to size it is held together with pressure great
enough to cause the whole number of mica discs to
practically become one piece. The assembly of a mica
core is shown in Figure 39 wherein the discs are sup-
ported at the bottom by a small metal plate fixed on
the electrode and held in compression by a nut at the
top.

Mica has the desirable quality of great mechanical
strength and consequent freedom from breakage or
cracking either from heat or accident and a mica plug
will stand a great deal of abuse and still continue to

Figure 39. — Laminations In Ordinary Mica Core of Spark

Plug.

do its work. Because of their mechanical strength
and ability to pass through the greatest changes of
heat and cold without fracture, mica plugs have been
used rather extensively in air cooled engines which
operate at temperatures a great deal higher than their
water cooled counterparts.

The disadvantage of mica as an insulator lies in the
fact that it is subject to a gradual penetration by the
oil and carbon deposits which creep in between the
discs or between the layers and strata of the mineral
itself in spite of the greatest practicable pressure.
With a new plug this tendency is well resisted, but
as the action of the electrical, mechanical and thermal
elements continues, there finally comes a time when

THE IGNITION CIRCUIT 95

the foreign substances have crept in near enough to
the central electrode to form a short circuiting path
and at this time the insulating properties of the plug
break down. This sort of failure gives rise to troubles
which are many times of a very baffling nature because
the plug is apparently in perfect condition and shows
no defect when the spark is allowed to pass in the
open air. Under compression, however, the* high ten-
sion current takes the path through the oil and carbon
between the layers of mica rather than across the air
gap.

Lava and soapstone insulators combine much of the
strength of mica with the high insulating proper-
ties of the porcelain. They also have some of the dis-
advantages of each in being subject to fracture easier
than the mica and offering less resistance to the pene-
tration of the carbon deposits than does highly glazed
porcelain. The exact composition of these several in-
sulators varies with the different makes of plugs and
they are often given descriptive names to distinguish
their make.

Shape of Insvlation. — The thickness of the insulat-
ing core between the central electrode and the shell
is always sufficient to prevent the passage of the high
tension current through it provided the material is
not broken or cracked at any point. The shape of
the lower end of the core is deterjnined with two-
objects in mind: to prevent the formation of a deposit
of carbon over the surface and to provide a com-
paratively great expanse of surface between the cen-
tral electrode and the shell over which any discharge
must take place when this surface is covered with a
layer of carbon, oil or moisture.

In Figure 40 are shown a number of forms of the

AUrOMOBII.E IQNITION

lower end of the core. That at A is the very gener-
ally adopted conical form. At B is a type which is
well back in the recess formed by the shell with the
idea of protecting the insulator from the dirfect action
of oil. At C and D are shown variations of the petti-
«oat type of construction in which any escaping cur-
rent would have to travel over both the inside and

Figure 40. — Forms of Spark Plug iDsulators.

outside surfaces of the lower end of the insulator
before reaching the metal of the shell. The form
shown at E provides a number of circular riba which
increase the surface and at the same time are designed '
to prevent the formation of carbon deposits due to
the fact that the thin edges of the ribs attain a degree

THE IGNITION CIRCUIT 97

of heat sufficient to bum . away any collection of
impurities.

Spark Plug Electrodes. — The ends or parts of the
electrodes between which the spark takes place must *
be of a material that will resist the heat of the dis-
ruptive discharge and of such shape and size that
they will not heat to incandescence and so cause pre-
ignition of the charge. The simplest and most gener-
ally adopted forms of electrodes are shown in Figure
40. A straight central electrode extends beyond the
insulator and a short length of wire is set into the
shell and bent with its end close enough to the central
electrode to form the desired gap.

At one time a considerable number of plugs were
provided with electrodes tipped with platinum or
platinum alloys because of this metal's resistance to
heat and corrosion. This practice adds greatly to the
cost of the plug and lately the platinum has been
generally abandoned in favor of nickel and various
alloys of nickel and steel for the two electrodes.
Nickel is one of the hardest of metals and is less
fusible than iron. It is not altered by the action of
the air or any common gases at temperatures ordi-
narily met with and forms a very satisfactory sub-
stitute for the more expensive platinum.

A number of plugs are made with the usual type
of central electrode or with but slight modifications
of this straight, small rod and with an extension of
the lower end of the shell which partially encloses the
sparking end of the plug and protects the end of the
insulator while acting as the shell electrode. Three
modifications of this type of plug are shown in Figure
41 in the upper row.

While a majority of spark plugs provide but one

AUTOMOBILE IGNITION

gap across which the spark must jump, others ate
constructed, to give two or more alternative paths or
gaps. The method is shown by the lower drawings of
Figure 41 as providing the shell with two or more
bent-over electrodes somewhat similar to the single one
generally found or by the use of some form of bridge
or loop. No more than a single spark will passi at any
one time in a multiple gap plug because the current
will always select the path of least resistance and inas-
much as some one pair of points will always be a little

Figure 41. — Types of Spark Plug Electrodes. Top: Single
Gap Forms. Bottom: Multi-Point Forms.

closer together than any other pair the spark will pass
at these points until they have burned away or been
beiit apart so that some other set forms a gap of less
resistance, when the current will take this ncfw path.
In this form of plug the short circuiting of any one
gap will short circuit the whole plug because all of the
current will then take this path of least resistance.

The shape of the points of the electrode between
which the arc takes place has something to do with
the effectiveness of the plug. It is a well understood

THE IGNITION CIRCUIT 99

fact that an electric discharge will take place easier
from a comparatively sharp point than from a sur-
face that is flat or rounded. For this reason it would
be desirable that the end of the electrode be rather
pointed and of small section. On the other hand a
small or pointed electrode will burn away much
quicker than one with more body of metal so that a
middle course, combining lasting qualities with fair
freedom for discharge, must be chosen in the design.
The pointing of the electrode could be carried to an
extreme in which case the discharge would be of the
brush type which does not provide the heat found in
the sharp disruptive spark that is formed between
fairly large points.

Spark Plug Gap, — The distance apart of the points
in the spark plug is of great importance in properly
firing the mixture. With a dynamo and storage bat-
tery as the source of current the spark becomes weaker
with increase of engine speed in all except true open
circuit systems and in these it maintains practically a
uniform strength at all speeds. At high engine speeds
the compression pressure is greater than at low speeds
and the resistance between the electrodes is therefore
greater with a fast running engine. With a magneto
as the source bf ignition current the spark is com-
paratively weak at low speeds and becomes stronger
and better able to jump the gap as the engine speed
and magneto voltage increases. In any case the gap
at the plug must be small enough so that the lowest
voltage produced with the engine at any ordinary run-
ning speed will be sufficient to pass across this space
in the plug and produce an arc hot enough to cause
good ignition.

For average conditions and in the average engine

100 AUTOMOBILB IGNITION

the distance between the electrode ends, or the spark
plug gap, should be between twenty-five and thirty-
thousandths^ of an inch. Under some conditions this
gap might advantageously be reduced to twenty thou-
sandths or increased to forty thousandths but these
would be the extreme variations.

With battery ignition ; should there be missing at
low speeds the spark plug gap may be slightly in-
creased in size, while for missing at high speeds the
gap may be closed a trifle more. With magneto igni-
' tion the reverse is true; low speed missing calls for a
smaUer gap and high speed missing for a larger gap.

Shells and Threads. — The first spark plugs used in
America were made with a metric thread because of
the fact that the details of the first cars were copied
from their foreign predecessors. This is a straight
thread and the plug is provided with a shoulder which
turns up tight against a finished surface around the
opening in the cylinder wall and with a gas tight
gasket of some form between the plug shoulder and
the body of the cylinder. Metric plugs are now
found in use on some motorcycle engines and air-
plane engines, on old American cars and on cars of
foreign make.

Later cars, and some makes of cars up to the present
time, use spark plugs having a one-half inch standard
pipe thread. This is a tapered thread which is
screwed into the cylinder opening until the tightness
of the fit between the male and female threads makes
a gas tight joint without the use of a gasket. Plugs
with a half inch standard thread may easily be
screwed into a hot cylinder so tightly that it is very
difiBcult to remove them at a future time, especially
trJien the engine has cooled. In this case a liberal

THE IGNITION CIRCUIT

101

application of kerosene allowed to remain around tlie
plug for some time will usually solve the difficulty.
The tapered thread is more likely to be damaged by

carelessness in handling than are the straight forms
and one or two chipped threads on the plug' or in
the cylinder will generally cause a leak of the com-

5MALLHEX.

LARSE HEX.

Figure 42.— Dim

Two modifications of an American standard spark
plug shell have now been adopt«d, both known as the
S. A. E. (Society of Automotive Engineers) Stand-
ard. The two iknda differ only in. 1\\%, sias, -A SbMs.
hexa^n part above the tVeada-, \>a.«. ot«> ^•^'i&- '^i**'

102 AUTOMOBILE. IGNITION

large hexagon being l^fe inches across the flats and
the small hexagon being % of an inch across the flats.
The outside diameter over the threads is % of an inch
and there are eighteen threads to the inch of length.
The plug is therefore oftentimes called a %"-18. The
S. A. E. plug has a straight thread and therefore re-
quires the use of a gasket in making a gas tight joint.
This gasket may be a separate member or' may be
formed over a fillet on the shell so that it is not
removable. The dimensions are shown in Figure 42.

Separable and Non-Separable Plugs. — The insulat-
ing core through which passes the central electrode
may be permanently fastened into the spark plug
shell, in which case the plug is of the non-separable
or solid type, or else the core may be held in place by
means of a packing nut and gaskets so that the center
assembly is easily removable for cleaning or replace-
ment. This latter type is called a separable or two-
piece plug. Both constructions are shown in Figure
43.

The non-separable plug has its insulating core
placed in the shell with a gasket between the lower
shoulder of the core and the seat in the shell. The
upper shoulder of the core is pressed down by the
metal of the shell or by some form of tapered wedge
and the metal of the shell above this shoulder^ is
beaded over to make a permanent and gas tight joint.
The plug of this construction has the advantage of
permanent alignment for the electrodes, which fixes
the gap distance, and of permanent gas tightness. Its
disadvantages are diflSculty of cleaning the insulator
and impossibility of renewal of the core and central
electro&e without an entire new plug.
TAe separable plug carries its msvx\a\ivTv^ o-oto. W

THE IGNITION CIIICUIT 103

tween two gaskets, one between the lower shoulder of
the core and the seat of the shell and the other be-
tween the top shoulder and the paeking nut which
holds the core in place. The core and central elec-
trode may be removed foom the shell by first unscrew-

ing the packing nut ; and after removal of the insulator
its surface may be easily cleaned of any aecumalations .
of carbon or oil. The disadvantages of this t^'S*. «-'»■
found in the danger of imsaligmn.«oX •al'CQfc <j?i^ -%««:&».

104 AUTOMOBILE IGNITION

on replacement and the danger of breakage of the core
because of screwing the packing nut into place too
tightly or else not tightly enough so that the core is
left loose in the shell.

In addition to their making gas tight joints, gaskets
are necessary in most forms of plugs because of the
difference in the rates of expansion for the metal of
the shell and the material of the insulator. Porcelain
and many kinds of insulating stone have widely differ-
ent coefficients of expansion from the steel and in sep-
arable plugs with insulators of these materials great
care should be exercised not to turn the packing nut
down too tightly because this wiU result in breakage
of the core as soon as the engine warms. A packing
nut should be turned into place just tightly enough
to hold the core firmly and to prevent the escape of
gas, but no tighter under any circumstances.

Spark Plug Location. — ^No form of spark plug will
give the results, of which it is capable if its location
and setting in the cylinder are not correct. In order
that an engine may run efficiently the time required
for the spread of the flame through the mixture should
be as short as possible, and to secure this result the
spark plug gap should be located within the cojn-
bustion space and not in a pocket or recess.

If the plug is so located that its points are placed
in a recess or hole that communicates with the com-
bustion space, as will be the case with a short plug
set in a thick valve cap, dead gas will accumulate
about the electrodes and cause missing and slow
combustion. With the gap inside the combustion
space proper, the spark comes into contact with fresh
clean gas and the flame will spread with maximum
rapidity. Such a correct setting is skoTni ^1 tloi^ Uit m

THE IGNITION CIRCUIT 105

Figure 44, while at the right is shown an incorrectly
pocketed plug.

It follows that the spark plug should preferably
be located in the immediate neighborhood of the in-
take valve in such a manner that it will be sur-
rounded by the fresh gas that enters during the
int^e stroke. If the plug is located near the ex-
haust, rather than the intake valve, there is a possi-
bility that the dead Exhaust gas collecting around
the points will cause missing and inefficiency.

In order to get the best results the plugs shoiild

be so set in the cylinder that cooled metal is in close
proximity to the sparking points as this setting will
eliminate overheating of the plug electrodes with the
consequent danger of preignition due to red hot
metal. This requires that the plug be set into a por-
tion of the cylinder that is at least fairly well cooled
by the water jackets in a water cooled engine.

On many engines the spark pln^g ia wA wftja '^Mi
cylinder wall in such Ei po^tiou\\«A"\\-^«s»s»'^l5«.'saj&».

106 AUTOMOBILE IGNITION

the water jackets and an extra long bodied plug is
required in order to prevent harmful pocketing of
the gases. With such a design the electrodes, and in
many cases a part of the end of the shell, extend be-
yond the threaded portion of the plug. There is then
danger of the electrodes becoming excessively hot or
that the metal of the shell will allow warping and
consequent change in the size of the gap.

The most commonly adopted position for the spark
plug is in the cap that covers the inlet valve with
engines having T or L head cylinders. With valves
in the head of the cylinder some other location must
be found and the plug is often set into the side of
the combustion space, or, if sufficient space remains,
into the head of the cylinder near the valves. Some
L and T head engines are built with the spark plug
.carried over the top of the piston rather than in the
valve pocket on the theory that the spreading flame
will more quickly reach the furthermost parts of
the combustion space with the spark taking place
near the center of the body of gas than would be the
case with the spark passing in one of the valve pockets.

Special Forms of Plugs. — To meet peculiar condi-
tions in various engines certain modifications of de-
sign are introduced into the spark plugs manufac-
tured by most makers. The condition most often met
with is one that calls for a plug varying from the
usual length either above or below the threads, that
is, either inside or outside of the combustion space.
To accommodate engines having the plugs set in
rather thick walls or passing through the water jack-
ets, plugs are made with extensions of both electrodes
and shell in varying lengths. To avoid interference
with such engine parts as water manifolds and va-

THE IGNITION CIRCUIT 107

rious support rods some plugs are made with the
length of the insulator outside the cylinder very short
in proportion to the whole length of the plug.

For use in engines not provided with pet cocks
a form of spark plug called a priming plug has been
developed which incorporates in the shell a small

Figure 45.— Priming Type of Spark Plug- (Chajnplon).

pet eoek or screw valve through which liquid gasoline
may be introduced into the combustion space or which
may be used for any of the other purposes that pet
cocks are designed for. The opening inside of the
shejl admits the fuel which is used for priming directly
- onto the end of the electrodes between which, tha

108 AUTOMOBILE IGNITION

spark takes place so that firing of the charge is made
sure. One form of priming plug is shown in Figure
45.

IGNITION WIRING

Cable, — Ignition wire or cable is usually desig-
nated by the name of the current it is designed to
carry. Primary wire for conducting the primary or
low tension current is made with a comparatively
large copper conductor and with a small thickness
of insulation over the copper. This form is most
satisfactory because the large area of conductor car-
ries the low pressure current with but slight loss in .
voltage due to the resistance of the cable. Secondary
wire has a smaller copper conductor than has the
primary but has a comparatively thick insulating
covering. The small wire carries the secondary cur-
rent because this current is of very low amperage
and the slight voltage loss is of little consequence
when dealing with thousands of volts pressure as is
the case here. The heavy insulation is required be-
cause of the high voltage which would force the cur-
rent through any lighter covering rather than send-
ing it across the high resistance gap at the spark plug.

All ignition cable is of the flexible variety, made up
of a conductor consisting of a number of strands of
very fine wire, the number and size of these strands
being sufficient to provide the necessary conducting
ability. Such a cable is called a stranded cable.
Over this conductor is generally placed an insulating
cover of compositions of rubber, although much igni-
tion cable is in use having its insulation composed
of layers of strip linen or cotton wound around the
conductor and then covered with woven fabric. In

THE IGNITION CIRCUIT 108

Bome cases this cloth insulation is combined with
one or more layers of rubber insulation also. Such
a cable is called braided or fabric covered. Methods
of fastening cable ends are shown in Figure 46.

Primary cable is often made with two or more
conductors, each covered with its own insulation, an4

the whole enclosed with an outer covering of fabric
and additional insulation. Such cables, called duplex,
triplex, etc., according to the number of separate
conductors in the cable, are used for lines requiring
that several circuits, or the positive and negative
Bides of one circuit, be carried between points

no AUTOMOBIL.E IGNITION

which allow the opposite ends of the several lines to
be close to each other.

Primary Cable. — Primary cable may be constructed
according to either of two methods, each method being
a standard recommended by the Society of Automo-
tive Engineers. Class *'B" cable is provided with an
Insulating covering composed of rubber compound
and fabric. The rubber is first covered either with an
overlapping strip of varnished cambric, or a cotton
braid, so saturated as to make it oil and moisture
proof. This first fabric is then covered with an outer
braid of strong protective character, preferably
glazed, and treated with at least two coats of insulat-
ing varnish. The rubber itself is 1/32 inch thick.
Such cable will withstand a pressure of 1000 volts
for one minute.

Class **C'^ primary cable will withstand 1500 volts
for one minute. The insulation of this class of cable
includes either two or three layers of varnished cam-
bric tape, then a closely woven cotton braid which is
treated to make it oil and moisture proof and finally
an outer braid of a protective nature which is treated
with at least two coats of insulating varnish.

Secondary Cable. — Secondary cable may be made
with plain rubber insulation, then having an outside
diameter of either seven or nine millimeters; or it
may be made with an additional covering of cotton
braid, when the outside diameter will be either 5/16
or 25/64 of an inch.

Good secondary cable will withstand 12,000 volts
for five minutes after the cable has been in water for
twelve hours and while it is still immersed. A one
foot length of such cable will withstand 20,000 volts
for five minutes.

THE IGNITION CIRCUIT

IIX

Positive

Negative

Positive
or negative

X3 Contact points

■^) Wire terminal

Coll or solenoid

Wires

(ssing without

connection

Electromasrnet

nnected wires

--i^AA/WW^— » Coil or resistance

ad connection

Lamps in multiple

Fuse

Condenser

( I •

Battery

Voltmeter

Ammeter

rifirure 47. — Symbols Commonly Used in Wiring Diagrrams.

112 AUTOMOBILE IGNITION

The life of secondary cable may be tested as fol-
lows: Remove the insulation' from each end of a five
foot length of the cable, solder one end of the cable
to one end of a steel rod of approximately the same
diameter as the cable, wrap the cable tightly around
this rod and solder the other cable end to the rod so
that the tight wrapping will be maintained. In this
condition, the cable should be exposed to the weather.
If the insulation is not properly compounded or vul-
canized, deteriorating effects, such as hardening, be-,
coming brittle and cracking, will develop in from one
to three months.

The physical characteristics of secondary cable in-
sulation are tested as follows : A section of the insu-
lation, not shorter than six inches, is taken from the
cable and marks are placed upon it two inches apart.
The cover is then stretched at the rate of twelve inches
per minute until these marks are six inches apart
after which it is released within five seconds. .One
minute thereafter, the distance between the marks
should not exceed 2% inches. The test specimen
should stand stretching until the marks are nine
inches stpsiTt before rupture. The ultimate tensile
strength of the rubber compound used in secondary
cable is not less than 1000 pounds per square inch
of cross section.

The characters and symbols generally used in mak-
ing ignition wiring diagrams are shown in Figure 47.

CHAPTER VI

IGNITION TIMING
PRINCIPLES AND REQUIREMENTS

The time at which the spark passes at the gap in
the plug is determined by the instant at which the
breaker contacts separate and at which the resulting
reaction takes place in the induction coil. With the
engine running at very low speeds, or when it is
desired, to crank the engine for starting, the spark
should take place just as the piston reaches top dead
center following the compression stroke or just as
the piston has started down on the power stroke.
Timing the spark for the engine is done by setting
the cam or other parts of the breaker to cause the
spark to take place at this instant. '

Because of the necessity for a definite and con-
trollable relation between the time of the spark
and the position of the piston in the cycle of strokes,,
the breaker cam and its driving shaft are positively
connected by means of gears or chains to the engine
crank shaft or cam shaft. With the usual types of
vertical ignition heads the ignition cam runs at the
same speed as the valve operating cam shaft of the
engine. With magneto types of ignition the breaker
cam runs at the same speed as the crank shaft of the
engine or twice as fast as the valve cam shaft.

113

114 AUTOMOBILE IGNITION

One spark must be provided for each cylinder
<iuring each second revolution of the crank shaft or
during each fourth stroke of the piston, which
amounts to the same thing inasmuch as the piston
makes two strokes, one down and the other up, for
each full revolution of the crank shaft. The valve
cam shaft of the engine runs at one-half the speed
•of the crank shaft and makes one full revolution for
each two revolutions of the crank shaft or each four
strokes, two down and two up, of the piston. A
l^reaker shaft running at engine cam shaft speed will
then likewise make one revolution for four strokes
of the piston. One of these strokes is the intake for
incoming fresh mixture, the next is used to compress
this mixture in the combustion space, the spark then
takes place, and the two following strokes are the
£ring stroke during which the burning gas expands
and the exhaust stroke in which the spent gas is
expelled from the cylinder. During the complete
Tevolution of the breaker shaft there must therefore
te one spark for each of the cylinders because each
'Cylinder will have one firing stroke during this time.
It therefore follows that the breaker contacts must
open once during the revolution of the breaker shaft
ior each cylinder to be fired. Each lobe or projec-
tion on the breaker cam causes the contacts to open
once so that there must be as many lobes or projec-
tions on the cam as there are cylinders to be fired by
this breaker, each of these lobes causing a spark for
one of the cylinders by opening the contacts once
•during the shaft's full revolution.

With the ignition breaker shaft and its cam travel-
dingr at engine crank shaft speed, or twice as fast as

IGNITION TIMING

115

the engine valve cam shaft, the breaker cam will
require just half the number of lobes that the slower
traveling type just described 'would require. Travel-
ing twice the number of revolutions in the same
length of time relative to the engine cycle, half the
number of cam lobes will do the same work.

In the last chapter two different types of breaker
were described, the closed circuit and the open cir-
cuit. It was also shown that the closed circuit type
of breaker opens its contacts when the forward side
of the cam lobe acts on the contact carrying arm,

<§)

Figrure 48. — Time of Contact Opening with Closed Circuit
(left) and Open Circuit (right) Type of Breakers.

while in the open circuit type the contacts are
allowed to open under the action of a spring when
the cam lobe passes out from under the bumper which
moves the breaker arm. These actions are shown in
Figure 48. At A is a closed circuit type of breaker
with its cam in position to just open the contacts
with continued rotation. At B is the open circuit
type with its cam also in position to allow the con-
tacts to open. To set or time the breaker showTi at
A the cam would be turned in the direction of its
normal rotation until one of the lobes just touched
the breaker arm bumper, as \w \Xv\^ ^Qi^\\a\wv *viw^ ^<^$^-

116 AUTOMOBILE IGNITION

tacts will be pushed apart with the slightest further
motion and the spark will therefore take place when-
ever one of the cam lobes reaches this position. In
timing the breaker shown at B the cam would be
turned in the direction of its rotation until one of its
lobes had pressed against the bumper carrying arm
which would cause the contacts to close, and the
cam would then be turned farther in this same direc-
tion until the cam lobe was just passing from under
the bumper as shown in the figure. At this time the
contacts would be separated by their spring and the
spark would therefore take place each time the cam
lobe reaches this position with reference to the
breaker arm.

TIMING METHODS

Various means are provided to allow the workman
to bring the breaker cam into the desired position.
With some makes and types of equipment the cam
itself may be loosened or removed from the shaft
which carries it, then moved to the correct position
for contact opening and again locked in place with
reference to the shaft. In other designs the shaft
which carries the breaker cam is so constructed that
it may be freed from the driving connection with the
engine either by means of a sleeve joint, a special
coupling or other device that suits the ideas of the
designer. The breaker shaft is, in such a type, turned
with the cam in place on the shaft until the cam has
been brought to the desired position. Still other
forms arrange that the breaker arm and contact
points be rotated around the breaker cam shaft until
the operating means on the arm is "^TO^x^Vt mtQ> «a<ili

laNITION TIMING 117

relation to the breaker cam that any rotation of the
cam. after this position has been reached will serve
to open the contacts.

To bring the breaker cam into its position for
timing it will be necessary to move the cam alone, or
else the cam with its shaft, in the same direction that
these parts are driven by the engine while in opera-
tion. In addition, any mechanical play or lag in the
several parts should be taken up as it would be with .
the engine running. The cam or shaft would there-
fore be moved in a clockwise or righthand direc-
tion in both A and B of Figure 48, this being the
supposed direction of rotation. In case it is only
possible to move the breal^er or ignition head hous-
ing, rather than the cam or its shaft, the housing
must be moved in a direction opposite to that of the
shaft and cam rotation. Reference to Figure 49 will
make clear the fact that rotation of the cam in the
direction indicated by the small arrow on the cam
would have exactly the same effect in bringing the
cam and bumper into certain relative positions as
would be produced by moving the housing with the
breaker contacts in the opposite direction, this
opposite direction being indicated by the larger
arrow just inside the breaker housing. In other
words it is required that the cam be moved forward
or the housing be moved backward until the cam
lobes are properly placed with reference to the
breaker arm bumper.

Timing Procedure. — Timing the ignition is the
operation by means of which the breaker mechanism
and the distributor are brought into proper relatlow
to the pistons of the various eyVviv^^A^^ V^ ^^vn^s^ ^>^^

118 AUTOMOBII-E IGNITION

passage of the spark at the correct instant dtiring
the engine's cycle. Because the breaker cam ts
designed to accommodAte the number of cylinders
on the engine with which used and because the dis-
tributor is likewiae built for this same number of
cylinders, timing the ignition for any one cylinder
will correctly time the operation of the breaker for

Housing-

all other cylinders and will also bring the distributor
into position so that placing the rotor and the apark
plug wires is all that is left to do.

Timing should be done by placing the piston in
one of the engine cylinders at that point in the cycle
at which the ignition spark should take place under
certain conditions of advance and retard. While the

IGNITION TIMING 119.

results will be exactly the same regardless of which
one of the cylinders is selected for the operation^
cylinder number one which is at the front of the car
is usually chosen and specified. It should be under-
stood that it is just as well to use number two or
any other cylinder should they be more accessible-
than number one. Timing may be done with the parts,
in position for a fully retarded spark, for a spark
half way advanced or for a fully advanced spark. It
is generally best, however, to use the proper posi^
tions for a fully retarded spark because it is quite
necessary that a sufficient retard be allowed in order s
to avoid tot) early ignition with the attendant dan-
gers to the mechanism or to the operator if the crank-
ing is done by hand. With the necessary retard
allowed for, the range of advance will be determined
by the construction of the breaker and the arrange-
ment of the advance and retard rods and levers.
This advance will then, in practically all cases, be
ample for all operating conditions, while were the
advanced position used in timing, the required retard
might not always be secured. From the above
explanation it will be clear why number one cylinder
and the fully retarded positions are selected in giving
timing instructions. In the chapters devoted te
complete descriptions ef the several makes and types-
of ignition apparatus specific instruction^ are given
for timing and these should always be followed when
piven. In the absence of specific instructions for
the particular equipment being handled the follow-
ing general directions may be followed:

First: Bring the piston of number one cylinder to-
top dead center between the compression and firing:

120 AUTOMOBILE IGNITION

strokes. The point at which the piston is in this posi-
tion (top dead center) may be determined in any one
of several ways. In case the flywheel is marked
these indications may be used. The marking may
specify the position by such characters as **TC 1 &
4" (top center for pistons one and four in a four
cylinder engine), "C 1 & 6'' (top center for pistons
one and six in a six cylinder power plant) or any
other Lit) ar kings whose meaning may be easily under-
stood. At one side of, or between the characters of
such a marking, there will be found a line drawn
from front to back of the flywheel and this line
should be brought directly on top of the flywheel or
directly underneath a pointer or arrow which is
fast<»ned to some stationary part of the engine.

If the flywheel of the engine is not marked it will
be possible to watch the piston's movement by re-
moving one of the valve caps, a spark plug, a cylin-
der head plug, a pet cock or any other part which
will provide an opening into the combustion space.
With such an opening the piston may be watched
with the aid of an artificial light or its movement
may be determined by inserting a wire or rod
through any available opening and observing the
rise and fall or movement of this rod as the crank
is slowly turned.

It is not' only necessary that the piston be brought
to top dead center, but that it be brought to the top
center between the compression and power strokes,
not to the center between the exhaust and intake
strokes. At the top center between compression and
firing, the combustion space is filled with a com-
pressed mixture of fuel gas and air ready for burn-

IGNITION TIMING 121

ing and it is at this time that the spark must take
place. At th^ opposite top center, following the
exhaust stroke, the cylinder's combustion space is
filled with dead gas which would not ignite.

The proper top center may be determined by
observing the action of the valves for the cylinder
being used for timing. With the valve stems or
springs uncovered, the crank should be turned slowly
until the exhaust valve of the cylinder being timed
is seen to open. With continued turning of the
crank this valve will then close and the inlet valve
of the same cylinder will immediately start to open.
The point during the revolution of the crank at which
the exhaust closes and the inlet opens is very near
top dead center, but this is the center between
exhaust and intake which not wanted for ignition
timing. One full turn of the crank will then bring
the piston into the correct position between the
compression and power strokes. As the piston nears
the correct position the crank should be turned very
slowly -while the piston movement is checked as
described. When the upward motion ceases the top
center has been reached and the cranking must be
discontinued before the piston again starts down.

The above method of bringing the piston into
position starts with the opening of the exhaust valve
which is almost two whole turns before the desired
top center will be reached. While this may seem to
entail an uncalled for loss of time it is recommended
tecause it gives the operator something which is
i^asUy seen and easily recognized (the exhaust valve
t^pening) to start with. It is of course true that an
eiiperienced workman, used to timing ignition

122 '. AUTOMOBILE IGNITION

devices, might start from whatever point in the
cycle he found the piston at and secure the same
results, still the slightly slower way is generally
best because it is the sure way. Should the inlet
valve be observed to just close when the engine is
fest cranked it will only be necessary to turn
until the piston is at the next top center which will
be the one between compression and firing. With
the piston brought into this position, by whatever
method, it should be allowed to remain stationary,
«,nd under no circumstances should the crank shaft
be turned the least bit until the breaker setting has
been made.

Second: After placing the piston, the breaker
advance and retard lever should be connected to its
operating rods and these rods should be connected
with the parts leading to the hand advance lever on
the steering wheel or column. The spark control
lever is generally the shorter one of a pair. With
the connections made, the hand lever should be
moved one way and the other while watching the
movement of the breaker housing or of the breaker
advance lever. With the hand lever moved from its
retarded position to the advanced position (away
from the operator in most cases) the breaker hous-
ing should move in a direction opposite to that in
-which the breaker shaft and cam revolve when
•driven by the engine. If the breaker housing does
not revolve, then the breaker mechanism should be
watched and the part of the breaker which carries
the arm and the movable contact point should
revolve in a direction the opposite of that in which
the shaft turns. Should the breaker housing or base

IGNITION TIMING 123

plate move in the same direction as the shaft turns
with the hand lever moved from Retard to advance,
either the connections are wrongly attached or else
the direction of the hand advance is the reverse of
that assumed.

In case the breaker cam, rather than the housing or
base, is found to move ; it should travel in the direc-
tion driven by the engine for advance and in the re-
verse direction for retard of the spark.

There should be little if any lost motion in the
connections, rods and levers. If lost motion exists
it should be taken up during the timing operations
by moving the advance lever on the breaker in the
direction of advance by hand until all slackness is
taken out of the connections. When ready to pro-
ceed with the timing after having checked the items
mentioned, the hand advance lever should be moved
from the fully retarded position about one-tenth to
one-four of its full travel toward the fully advanced
position. With the lever thus moved and the lost
motion taken up, the breaker housing should be
allowed to remain in this position.

Third: The cam or the breaker cam shaft should
be set to just open the contacts. If the breaker is
so constructed that the cam may be loosened from
its shaft this should now be done. If the breaker
cam is permanently secured to its shaft it will gen-
erally be found that the shaft is in two parts, one
part carrying the breaker cam while the other part
is attached to and driven from the engine. These
parts of the shaft may be fastened together for driv-
ing purposes by m^ans of one or more set screws in
a sleeve, by a clamping joint or by any one of several

124 AUTOMOBILE IGNITION

types of adjustable couplings. By whatever means
fastened together, the two parts of the shaft will
have to be disengaged for timing purposes.

If neither of the above conditions obtain ; that is,
if the cam is secure on its shaft and the shaft is not
divided, it will be necessary to take the breaker shaft
driving gears out of mesh or to uncouple the driving
chain if this method of drive. is used. In any event
the parts driving the breaker cam shaft should be
disconnected so that movement of the breaker cam
is possible without moving the piston and crankshaft
of the engine. It is possible that the breaker cam
and its shaft cannot in any way be disconnected
from the engine driving parts and in this case it will
be necessary to complete the timing by changing the
length or relative positions of some of the advance
and retard connections to allow turning of the
breaker housing rather than turning of the cam.
This condition is rare and will not be immediately
considered because of the possible confusion in the
following instructions.

With the breaker cam free to revolve it should be
slowly turned in the direction it runs during the
engine's operation until the contact points are seen
to close and then to just separate. The cam should
remain in the position at which the contacts barely
start to separate because it is at this instant that the
spark passes. With the cam, the control connections
and the piston in the positions described the cam
shaft drive should be secured so that this relation
will be maintained. In some types of equipment one
particular spark plug wire from the distributor is
supposed to lead to the plug in number one cylinder,

IGNITION TIMING 125

the distributor cap being generally marked with the
numeral **1" if this is the case. In such an event it
will be necessary to turn the cam or the cam shaft
in the breaker until the distributor rotor, when put
in place, will carry the high tension current to the
terminal thus marked. With the rotor brought to
this position approximately, the cam may then be
slowly turned in the direction it will be driven until
the contacts just commence to separate. As far as
the breaker, and the instant at which the spark takes
place, is concerned the ignition has now been prop-
erly timed and it only remains to take care of the
distributor and the wiring to the spark plugs.

The circuit tester described in Chapter Fourteen
may be conveniently used in timing to determine the
instant at which the contacts separate without
depending on the eye to note this movement. With
all external low tension wiring connections removed
from the breaker one of the leads from the circuit
tester should be connected with the breaker terminal
which leads to one of the contact points. The
remaining line from the circuit tester should be
placed in contact with the metal of the engine near
the breaker if the other breaker contact is grounded
(the usual practice) or, in case both sides of the
primary circuit are insulated, the second circuit
tester line should be touched to the breaker terminal
which connects with the second contact point. With
the contacts closed the test lamp will now light and
during the operation of timing, the breaker cam or
housing may be moved as described until the lamp
lights, indicating that the contacts are together, and
then moved until the lamp goes out which indicates

126 AUTOMOBILE IGNITION

that the contacts have opened and that this is the
position in which the breaker will cause a spark.

FIRING ORDERS

Contrary to what might naturally be supposed, the
various cylinders of an engine do not fire one after
the other in the order of their number or position
in the engine. DifEerent orders of firing are neces-
sary for reasons affecting the strength, balance and
vibration of the engine while running.

In specifying the order in which the cylinders fire
it is given according to the number of the cylinder.
Number one cylinder is always at the front or next
the radiator, number two is immediately behind
number one and so on, this applying to four and six
cylinder engines. With engines having eight or
twelve cylinders there are two' rows of cylinders so
that according to the foregoing rule there would be
two number ones, two number twos, etc. The cylv
inders of such an engine may be designated by num-
ber one left and nuntber one right according to their
position as viewed from the driver's seat when facing
forward, or they may be numbered consecutively
from one to eight or from one to twelve, in which
case number one is generally the left hand cylinder
next the radiator, number two is the right hand cyl-
inder next the radiator, number three the left hand
cylinder immediately back of number one and so on
through the entire number, alternating from left. to
right so that all the odd numbers are on the left
hand side and all the even numbers on the right. In
some cases eight and twelve cylinder engines have

IGNITION TIMING

128 AUTOMOBILE IGNITION

had their cylinders numbered from one to four or
one to six on either the left or right hand side of the
engine and from five to eight or from seven to twelve
on the other side.

A four cylinder engine may fire in either of two
orders ; 1-3-4-2 or else 1-2-4-3. No other firing order
is mechanically possible. An eight cylinder engine
is in reality a combination of two side by side four
cylinder engines on one crank case. The cylinders in
each set of four must fire after one another in either
one of these orders when the set on the other side of
the engine is not taken into account and whatever
firing order is selected for the cylinders on one side
of the engine must be followed for those on the other
side. In firing an eight cylinder engine, power
strokes occur on opposite sides of the engine alter-
nately, that is, after a cylinder on the left hand side
fires it is followed by one on the right, then by
another on the left and that in turn by one on the
right. The firing and numbering of the cylinders in
a twelve cylinder engine follows the same principles
as explained for the eight cylinder, this type of
engine, however, being a combination of two six cyl-
inder sets and the complete engine firing its cylinders
according to one of the combinations or orders pos-
sible with six cylinders.

Determining the Firing Order, — The firing order
of any engine may be easily determined by watching
the action of the valves because it is evident that the
valves will open and close in the same order in which
the cylinders fire. To make this observation select
either the exhaust or intake yalves, uncover their
springs or stems so that the movement may be seen

IGNITION TIMING

129

and slowly crank the engine until the valve of num-
ber one cylinder commences to open, this being indi-
cated by the spring starting to compress.

With a four cylinder engine the next valve to open
will be either number two or number three. If num-
ber two, the firing order is 1-2-4-3, and if number
three the firing order is 1-3-4-2. This next valve will
open one half turn of the crank after that on number
one cylinder opens.

With a six cylinder engine the valve on cylinder^
number four or five will open next, depending
on the construction of the engine. The valve which
follows number one will open one-third of a full turn
of the crank after number one starts to open.

Practically all six cylinder engines fire in the order
1-5-3-6-2-4 or in the prder 1-4-2-6-3-5, the f onfter being
the most popular, as indicated by the following par-
tial lists.

Cars whose engines fire 1-5-3-6-2-4 :

Apperson

Lexington

Paige

Auburn

Locomobile

Peerless

Case

McFarlan

Pierce

Chandler

Madison

Eoamer

Dorris

Marmon

Saxon

Hudson

Mitchell

Scripps-Booth

JeflPery

Moon

Steams

Jordan

National

Studebaker

Kissell

Oakland

Oldsmobile

Overland

VeUe

130 AUTOMOBILE IGNITION

Cars whose engines fire 1-4-2-6-3-5 :

Buick Haynes Reo

Chalmers Owen Stephens

Franklin Packard
Grant

With an eight cylinder engine the opening of the
valve for number one cylinder will be followed after
one fourth of a complete turn of the crank by the
opening of one of the valves on the opposite side of
the engine. With an engine having twelve cylinders
the valve next to open after that on number dne cyl-
inder will be on the opposite side of the engine and
will start to open one sixth of a full turn of the
crank after valve number one. <

One of the most popular firing orders for eight
cylinder engines is given' below; the numbers repre-
senting the cylinders in the two blocks from front to
rear, number 1 being toward the front, while the letter
L, following, indicates a cylinder in the left hand block
and the letter R, one in the right hand block. This
firing order is found on Apperson, Cadillac, Cole,
King, Oldsmobile and Peerless cars, as well as on
other makes.

1L-2R-3L-1R-4L.3R-2L-4B. ^

Among the twelve cylinder engines, those made by
Packard and Haynes use a firing order based on the
six cylinder otder, 1-4-2-6-3-5 ; the resulting arrange-
ment then being, with the letters L and R used as for
the explanation of eight cylinder engines just given:

lL.3R-4L-5R-2L-lR-6L-4R-3Lw2R-5L-6R.

A twelve cylinder firing order, based on the six cyl-

IGNITION TIMING 131

inder order 1-5-3-6-2-4, is as follows, this being found
on National and Enger ears :

1L-2R-5L-4R-3L-1R-6L-5R-2L-3R-4L-6B.

With the erank turned slowly the order in which
either exhaust or inlet valves act should be noted,
either in writing or mentally because it will be nec-^
essary to attach the spark plug wires to the dis-
tributor in such a way that the high tension current
flows to the cylinders in this same order, thus allow-
ing correct firing and causing the spark to pass ii^
the cylinder whose fresh gases are under com-
pression.

DISTRIBUTOR WIRING AND TIMING

Afte^: the opening of the breaker contacts has been
properly timed for the engine it will be found that
with the distributor rotor in position on its shaft or
gear the distributor segments, brushes or pins will
be in such relation to the rotor that the secondary
current passing. upon opening of the contacts will
flow to one of the terminals on the distributor cap.
If the timing of the breaker has been done by bring-
ing the piston of number one cylinder to top firing
center, then a wire should be placed between this
distributor terminal to which the rotor sends the
current and the spark plug in number one cylinder.

It is now necessary to observe in which direction
the distributor rotor turns when the engine is run-
ning or is being cranked. This direction of revolu-
tion will bring the rotor into ^o^VWftw ^^ *^^ ^'e^is^

132 AUTOMOBILE IGNITION

opening of the breaker contacts to send the high
tension current to a distributor terminal on one side
or the other of that terminal which has been con-
nected with the spark plug in cylinder number one.
This next distributor terminal to receive the current
dshould be connected with another wire to the spark
plug of the cylinder next to fire according to the
firing order of the engine being worked on, an
explanation of how to determine this firing order
having already been given. With further turning of
the rotor as the engine is cranked the current will
1)0 led to the next terminal in order around the dis-
tributor cap and this terminal should then be con-
nected with the third cylinder to fire. This same
method should be followed, connecting the wires
from the spark plugs in the order of the firing on
that engine with the remaining terminals on the dis-
tributor in their order around the distributor cap
And in the direction of the rotor's turning while in
actual operation.

It will be noticed by observing the construction of
any distributor that the rotor will deliver its current
to the connection for one of the terminals during a
•considerable part of a revolution. That is to say,
the rotor might be turned some distance either for-
ivard or backward and still pass the secondary cur-
rent to the terminal connection without the necessity
of having this current pass across any additional gap
between the rotor and the terminal connection. This
construction is adopted to allow for the advance and
retard of the breaker because this advance and
retard will cause the spark to pass either earlier or
J&ter in the turning of the distributor.

IGNITION TIMINa 133:

In Figure 51 this construction is shown by a
\ i^aker cam and contacts together with a distributor
votor making connection with a stationary terminal
connection in the distributor cap. At the upper
left is shown the fully retarded position, with the-
breaker cam just about to open the contacts and witL
the distributor rotor segment making connection,
with the terminal at the extreme rear end of the
rotor's segment. As the breaker housing is moved
to its advanced position the arm L and its contacts^
travel around the cam in a direction opposite to that
in which the driving shaft turns until the parts are
fis at the upper right. The spark will then take
place with the distributar rotor not so far around
in its travel but in the right hand position where^
the rotor segment makes connection with the ter-
minal at the extreme forward end of the segments
The distributor rotor is carried by the same shaft
that operates the cam and of course turns in the sam^
direction and at the same speed as does the canu
Were the outer end of the rotor segment any shorter
than shown or were it possible to put the rotor in.
the wrong position on its shaft, then the segment
might not be in contact with the terminal and th©^
current would be required to jump an additional gap-
or else to fail to pass because of the added resistance^
A majority of distributors in which the rotor is car-
ried by the upper end of the breaker cam shaft are^
so built that it is impossible to replace them in any
other position than the right one so that no trouble^
should be encountered from this cause.

At the bottom of Figure 51 is shown a breake.ic «e^^
distribntor with the rotor camfc^ on ^ %^'Kt ^skv^i^ss^

134 AUTaMOBILrE IGNITION

from the shaft that carries the breaker and mrming
^t one half the speed of the breaker shaft. This is
the type generally used in magnetos and in some
<;ases adopted for battery ignition systems. It is
Yery essential that the distributor gear be correctly
meshed with its pinion on the breaker shaft, other-
ivise the connection between the rotor and the cap
terminals will be made at the wrong time and arcing
will occur between these parts either during the time
of advanced or retarded spark and in some cases a
spark will be delivered to the plug of a cylinder
which is not ready to fire.

This geared type of distributor is shown retarded
at the right and fully advanced at the left. As re-
tarded, the rotor is just making contact with the last
part of one of the segments, which, in the type shown,
are stationary and set into the distributor cap. When
in the advanced position the rotor has not progressed
as far and the spark takes place earlier in the piston's
stroke. The rotor is accordingly making contact with
the first part of the segment with which it comes in
contact. The segment must then be made long enough
fio that the rotor is in contact with it from full retard

^ to full advance.

In the type of mechanism shown at the bottom the
gear which carries the distributor rotor and the
pinion on the breaker shaft are usually marked on
the teeth that should be in mesh so that correct
replacement is rendered easy. In case the device is
built for either right or left hand rotation (viewed
from the driven end of the breaker shaft) the dis-
tributor gear is generally marked with two points

^or meshing, one being indicated by \h& letter L for

IGNITION TIMING

135

Flgrure 51. — Relation of Distributor Rotor to Ses^Kv^xv^-. •^^"^*«

Battery Type. BoUoitv; "M.agtv^\.o '^^v^. X^fe'l-X.*.

Retarded. R\gYvl; AOLNax^it^^.

136 • AUTOMOBILE IGNITION

left hand rotation and the other by the letter R for
right hand rotation.

Should the gears be improperly meshed so that an
additional gap occurs in the distributor it will cause
missing and irregular action with the engine ngi-
ning. The effect in the distributor will be to cause
burning of the distributor cap segments because of
the incorrect position of the rotor when the spark
takes place. Should examination of such a dis-
tributor show bifming and pitting of the segments
at the end with which the rotor first comes in con-
tact during its revolution, it indicates that the dis-
tributor gear is meshed too far back and it should
be turned one or more teeth ahead with reference to
the breaker shaft pinion, while if the burning is at
the end of the segments at which the rotor leaves
contact, the distributor gear should be set back one
or more teeth. With the distributor gear set too
far ahead the missing will occur with a retarded
spark and with the gear set too far back the missing
will be most noticed with an advanced spark.

_ ADVANCE AND RETARD

At first thought it would seem that the spark
should pass through the infiammable mixture of fuel
and air when the piston is at the top of its stroke
and just ready to descend because it is at this time
that the pressure of the t)uming mixture will do the
most good in driving the engine. However, upon
reflection it will be seen that this timing of the spark
is not early enough to give the desired results except
when the engine is being cranked or is running at the
Jowest possible speeds. Some of the factors affecting
tlie timing of the spark and t\v^ timfe «A. yrhich the

IGNITION TIMINa 137

breaker cantacts must separate were mentioned in
Chapter One and it will be well to review these points
in their practical applications.

Depending on the type of breaker and ignition
mechanism used it will be necessary to cause the
contacts to open more or less before the spark must
pass in the cylinder. This early opening or advance
is called for because of the electrical lag and because
of a certain period of time which is required for the
operation of the mechanical parts of the breaker,
this latter being called mechanical lag. Electrical
lag is in reality a magnetic lag or sluggishness with
which the magnetizing force of the primary current
in the coil produces its magnetizing effect on the iron
core. This lag is accentuated by the tendency of
the iron core to resist, and therefore, retard magnet-
ization. In order to compensate for these two effects
it is necessary that the breaker contacts open a cer-
tain time before the spark must pass and these con-
ditions affect the ignition system whether the engine
is^unning slowly or at a high rate of speed.
^ The most important element affecting the timing
of the ignition, as it concerns the amount of advance
given the breaker mechanism, is the time required
for the flame to travel from the spark at the plug
through the entire body of inflammable mixture in the
combustion space and by causing this mixture to
fully ignite to produce the maximum pressure on
the piston head. The length of time required, meas-
ured in fractions of a second, for the flame to travel
to the farthest points in the combustion space is very
nearly constant regardless of the speed of the engine
and of the piston's travel, Oii \Xife q^^t \axs^^ ^^'^

138 AUTOMOBILE IGNITION

piston speed, or the rate of travel with which the
piston approaches the cylinder head, is of course in
direct ratio to the speed of the engine. -

It is true that the spread of the flame is affected
by the degree of compression under which the gases
are held when the spark passes and this compression
pressure generally increases slightly with engine speed
because at high speed the minute leaks from the com-
bustion space do not allow as much of the gas to
escape as at low speed. This condition of greater
compression increases the speed of flame travel and
causes the maximum pressure to occur quicker, thus
tending in some degree to advance the effective
timing of the ignition. It is also true that the pro-
portions of fuel and air in the mixture affect the
travel of the flame, but inasmuch as these conditions
are not variable in any great degree without change
in the carburetor action or adjustment, they may be
neglected in determining the necessary spark
advance. It is, of course, assumed that the fuel mix-
ture is of the best possible proportioning and that the
mixture is being properly heated.

The effect of increasing speed of the piston,
together with practically constant speed of flame
travel, then remains as the principal reason for pro-
viding spark advance for the breaker. Considering
an engine with a six inch stroke turning at one hun-
dred revolutions a minute (a practical cranking
speed) the piston will travel through one hundred
times its complete up and down movement, twelve
himdred inches, in one minute which is a speed of
twenty inches each second. If now we assume that
the Same requires the one hundredth part of a second

IGNITION TIMING

13»

to fully ignite all the gas it will be possible to arrive
at any desired spark advance for this speed.

Referring to illustration A in Figure 52 we will
assume the above mentioned conditions of flame
travel and piston speed, and, for example, that full ig-

^S^^ss^^

%%>w>a:v>xwnn>

Flg-ure 52. — Relation of Spark Advance to Piston Speed and

Travel.

nition of the gases is wanted with the piston at top
dead center, which position is indicated by line Y.
The piston is supposed to be moving at the rate of
twenty inches each second and in the one hundredth
part of a second required ioT ?l^isv^ Xx^^^^^Ocsfe^^^'^^

140 AUTOMOBILE IGNITION

will move one one-hundredth of twenty jnches or
2/lOth of an inch. Referring to the illustration, the
line X (the top of the piston) should then be 2/lOtJis
of an inch below top center when the spark passes
because with this advance of the spark the flame will
.have fully- ignited the gases just as the piston
reaches the extreme top of its stroke. This advance
of 2/lOth of an inch is an advance equivalent to
l/30th of the entire stroke or about 20°, and would
be excessive for cranking in actual practice.

Then referring to B in the same figure, assume
that the time for Complete ignition after the passage
of the spark is still the same, 1/lOOth of a second,
tut assume the engine crankshaft speed to be 2000
revolutions a minute. In 2000 revolutions the piston
will travel up and down (six inches each way) 2000
times in a minute and will travel 24,000 inches a min-
ute or 400 inches a second. In order to still allow
the flame 1/lOOth of a second to fully ignite the gas
it would be necessary to cause the spark to take
place four inches (or two-thirds of a stroke) before
top center because the piston will travel this four
Inches in 1/100 of a second and upon arrival at top
center find the gases fully ignited. This speed would
l)e too great for practical use in an engine having a
six inch stroke, but is used simply to show the great
-advance required in spark timing to make up for the
increase in piston speed.

As a practical illustration of the advance required
as measured in degrees of crankshaft or flywheel
travel, consider the case shown at C in Figure 52.
The flame travel is here assumed to require l/120th
of a second and the engine to be turning at a rate

IGNITION TIMING 141

of 1200 revolutions a minute. The piston speed will
then be 14,400 inches a minute or 240 inches a sec-
ond. Traveling at this rate the piston will move two
inches in l/120th of a second, or the distance
between the top of the piston head as shown and
the dotted line indicating top center. With a six inch
stroke this two inch advalice will correspond to a
crankshaft travel of nearly 60° as shown and this
amount of advance will be required for the opening
of the breaker contacts before the piston reaches
top center. In actual practice, modem ignition

Figure 53. — Spark Advance Caused by Movement of Breaker
Arm. Left: Retarded. Right: Advanced.

devices are constructed to provide a range of from
30° to 60°, and in rare cases even greater advance
than this.

The spark advance may be secured through move-
ment of the breaker housing and base plate together
with the contact arm and contacts, or else by moving
the cam in relation to the shaft by means of which
the breaker is driven. With the method of mov-
ing the housing and contacts, the advance is se-

142 AUTOMOBILE IGNITION

<;ured by turning the housing around the shaft in
a direetio,n the opposite of that in which the shaft
turns. The effect of such movement of the contact
carrying member is shown in Figure 53 by illustrating
& cam with but a single lobe rotating in a clockwise
or right hand direction. The direction of rotatioiTof
the cam and its shaft is shown by the arrow A and
the direction in which the breaker arm and contacts
«hould move for advance is shown by arrow B. It
vrill be seen that movement of the arm and contacts
in the direction of B would cause the bumper to be
•struck by the cam and the contacts to be separated
before the cam had reached the position 'shown, or,
in other words, earlier in the operation of the engine
«,nd in the stroke of the piston. The retarded posi-
tions are shown at the left of the illustration and the
-advanced positions at the right. In the advanced
positions it will be seen that the lobe on the cam will
fitrike the bumper on the arm some time before it
would do so when retarded and by the amount of
this movement of the breaker housing and arm with
the contacts, the degree of advance is' determined
and suited to the speed and running conditions of
the engine.

In some types of construction the breaker arm
and contacts remain stationary and the cam itself
is moved relative to its shaft. One method of secur-
ing this result is shown in Figure 54 which shows one
form of hand advance used with Delco ignition
devices. The shaft which carries the breaker cam is
in the form of a tube and a helical slot is cut through
the wall of this hollow driving shaft. A smaller
shaft is carried inside of tliis \v.o\\o^ \>\3!o^ ^tA "Okvs*

IGNITION TIMINO 148

smaller shaft is driven from tlie engine. A vertical
slot is cut down ttirough the smaller shaft and a pin
passes through both the straight slot in the small
shaft and the helical slot in the cam shaft. This pin
is held by a collar which is adapted to slide up and

—Helical Slot Advi

(Delco).

down on the outside of the hollow shaft. If the
collar which holds the pin be moved up or down,
the movement of the pin along the helical slot
will cause the tubular shaft with the breaker cam
to turn with reference to the BmallCT wA\ft- ^^^^ •*»&.
tbJB turning will either Be in ftic AVcftt'WQtv <A "cAs^wso.

144 AUTOMOBILE IGNITION

or in the opposite direction, depending on whether
the collar and pin are moved one way or the other.
In such a mechanism it is obvious that if the cam
and its shaft are moved in the same direction that
they normally rotate, the ignition timing will be
advanced because the lobes of the cam will then act^
on the breaker arm earlier in the piston stroke and
crankshaft revolution than they would otherwise.
On the other hand, the ignition will be retarded by
moving the cam in the direction opposite to that of
rotation because this practically turns the cam a
part of a revolution backward so that it acts on the
breaker later than it otherwise would.

AUTOMATIC SPARK ADVANCE

It has been shown that the principal factor govern-
ing the degree of spark advance is the speed of the
engine and it is because of this fact that a number
of automatic devices have been adopted which allow
this speed of the engine to effect a corresponding
advance in the time at which the breaker contacts
open. All of these mechanisms make use of the
centrifugal force generated by weights which are
driven by the engine. The force thus generated is
opposed by the tension of various forms of springs
and the balance between the spring tension and the
power of the revolving weights determines the spark
advance.

Automatic spark advance has the advantage of
causing the mixture to be ignited at the time that
is theoretically correct without attention by the
operator and in the case of inexperienced or careless

IGNITION TIMING 145

users this is an undoubted benefit to the engine.
Automatic advance avoids the penalties of a too late
spark which include waste of fuel, loss of power,
overheating of the engine and burning of the lubri-
cating oil and the valves. It also avoids the dangers
from a spark that is timed too early, these including
such things as damage to the electric starting motor
and battery or to the person cranking the engine by
hand, damage to the bearings and shafts because of
the strains which, are indicated by knocking and
again, loss of power and consequent waste of fuel.
Among the disadvantages of automatic means of
spark advance are the added mechanical complica-
tion which comes with any additions to^ the power
^ plant and the unreliability and trouble found with
some fprms of advance devices.

One of three well known centrifugal devices; tan-
gent weights, fly-ball weights or a ring governor;
is generally adopted. In the arrangement shown in
Figure 55, the weighted arms W are mounted on the
base plate of the housing H by the pivot pins P. The
housing and its base plate are driven from the
engine and increase their speed proportionately with
that of the engine. The breaker cam is carried by
the shaft D to which is fastened the collar C with
which in turn, engage two pins on the inner ends of
the weighted arms, these pins fitting into the slots
of the collar as sho^vn. As the device is rotated by
the engine in the direction indicated by the arrow
the outer ends of the weighted arms tend to fly away
from the center. In doing so, the tension of the
springs S must be overcome and as the arms pivot
on the pins P, these springs are bent to a greater and

greater degree depeuding on the engine speed. As
the anus move outward the pins at their inner ends
cause the collar C to turn with reference to the hous-
ing and through the collar the shaft D carrying the
breaker cam is also turned some distance in the same

(St

direction that the whole mechanism is being driven
by the engine. This inovement of the shaft, by mov-
ing the cam of the breaker farther ahead in the direc-
tion of rotation, advances the time of spark timing.
TJie degree of advance for any given engine speed is
■determined by the shape, sUengtb. aai. \.fem\Wi ^1

IGNITION TIMING 147

the Springs S, which conditions can of course be
changed to Emit different engines.

In Figure 56 is illustrated another type of gov-
ernor which has been used on a groat many Atwater
Kent installations. This mechanism is carried in a
cylindrical housing directly underneath the breaker

Figure B6. — Governor for Automatic Advance (Atwater

and distributor and on a vertical shaft which is
driven at one half the speed of the engine crank
shaft. This governor consists of two pairs of weights
A, eaehpair being pivoted together at their centers,
and in addition to the weiRhts the two double arm
brackets B. "When the drive shaft is revolved by
the engine the weights tend to fly away from the
center and in doing so they cause the arms B to

148 AUTOMOBILE IGNITION

revolve a part of a turn with reference to the shaft
D, In order that the weights will not move away
from the center too easily and thus give too great an
advance at low engine speeds the springs E are bo
attached to their tn^ekets and the weights that they
oppose the outward movement of the weights. Each
weight is in effect a bell crank lever with one point

Spark J

of connection pivoted on the arm and the other point
of connection pivoted to the weight. The four
weights work in the same direction at the same time
against their four respective springs.

In Figure 57 is shown a section through the first
type of automatic advance governor used with Delco
equipment. This governor is of the ring weight type
and is used in connection with the advance method

IGNITION TIMING 149

which has already been described and illustrated in
Figure 54. In the case of the automatic governor the
ring by which the pin is carried is actuated by the
force of the revolviAg ring in place of by manual
means. It will be seen from the illustration that the
ring is supported by a piyot passing from side to side
through its wfdth and that on one side of the ring
and inside the circle is an extension or knob which
engages a slot cut around the ring and which
operates the advance pin in the slots of the shafts.
The ring weight is normally held in the slanting posi-
tion as shown, by the tension of a coiled spring
around the shafts and above the actuating ring.
With increase of engine speed the ring weight tends
to straighten out and revolve with its axis in line
with the center line of the revolving shafts, that is,
the body of the ring weight attempts to get as far
away from the shaft as possible. In thus moving
against the tension of the spring the lug on the ring
weight lifts the collar and causes the pin to move the
breaker shaft relative to the engine driving shaft. .
The type of automatic advance used with later
types of Delco equipment is shown in Figure 58.
Above is shown a vertical section through the de-
vice and below is the top view of one of the weights
with its method of engaging the breaker cam shaft.
Three centrifugal weights are carried around the
breaker shaft, and on the shaft which carries the
breaker cam are three extensions which are acted upon
by hooked shaped members on the ends of the weights
and near the pivots by means of which the weights are
supported and driven. As the speed of the engine and
of the driving shaft increase, the weights tend to

AUTOMOBILE IGNITION

IGNITION TIMING 151

fly out and this tendency is resisted by the coiled '
springs, one of Which is shown attached to its weight
in illustration, Figure 58. The movement of the
weight causes the hook to pull the three armed spider
farther around in the same direction that the shaft
rotates and the ignition timing is thereby advanced.
The Eisemann magneto with its automatic advance
is shown in Figure 59. TJiis is a modification of
the fly-ball type of governor adapted to change the
relation between the shaft driven from the engine
and the shaft passing through the armature and to
the breaker of the magneto. To this armature and
its shaft is attached a box-like guide within which
is carried a block designed to slide back and forth
in the guide. Through this block is a hole and two
slots or keyways which are so cut that they fit over
and engage two keys on the outside of the driving
shaft. These driving shaft keys and the keyways in
the sliding block follow a curved or screw-like path
around the shaft and through the block so that if the
block be slid along the shaft the curving of the keys
will cause the block to turn for a part of a revolu-
tion about the shaft as it slides. Inasmuch as the
block is carried inside of the guide which is fastened
to the armature shaft the armature and breaker shaft
will likewise revolve for this same part of a revolu-
tion with reference to the driving shaft. The arma-
ture shaft then drives the armature and breaker
through the two keys, the square block and the
guide. To the block are pivoted two arms of the
weights shown in the illustration and the other arms
of these weights are fixed to the guide on the arma-
ture. As the driving shaft Tota\,^^ m ^x^^^wSSss^X^

AUTOMOBILE IGNITION

the 8peed of the engine, the weights tend to fly out^
ward and, according to the throw of the weights, the
armature and breaker are shifted wiUi respect to

Figure 59. — Fly-Ball Type oC Automatic Advance Governor.

Top: Governor. Bottom: Ma.g'neto Installation

(Blsemann).

the driving shaft, thas advancing the time of igni-
tion. As the block is drawn endwise by the weights
a coiled spring carried around 'ttie shaft is com-

IGNITION TIMING 153

pressed and the tension of this spring, opposed to the
force of the weights, determines the amount of
advance.

V This type of automatic advance mechanism may
be suited to various engines and provide maximum
advance of from twenty to sixty degrees by using
shafts having keys of various pitches and by using
springs with varying strength. In common with
practically all other automatic advance devices
there is no provision for adjustment once the engine
has been properly fitted and no adjustment should
be made or attempted.

In the Westinghouse advance shown retarded at
the top and advanced below in Figure 60, the weights
themselves act as the breaker cam and due to their
shape they open the breaker contacts earlier and
earlier as the speed of the engine and the driving
shaft increase. Two weights are provided which
are pivoted in the usual way and whose movement
from the normal position at low speed is opposed by
two flat springs which are bent by lugs attached to
the weights as the speed increases.

The breaker arm is moved to close and open the
contacts as the outer ends of these weights come in
contact with the bumper attached to the arm. As
the engine speed increases and the weights move
outward, their new position causes them to remain in
contact with the bumper for a greater part of the
revolution, thus holding the breaker contacts closed
for a greater length of time and also causing them
to operate earlier during the stroke of the piston.
Thus the advance mechanism performs the dual func-
tion of advancing the time of ignition and also of

151

AUTOMOBILE IGNITION

maintaining the heat of the apark because the greater
number of degrees during which the breaker con-
tacts are together compensates for the greater speed
of the parts and the actual time during which the

Figure 60. — Automatic Advance Weights Acting as Breaker

Cams. Top: Retarded. Bottom: Advanced

(Weatinghouae).

contacts are closed, as measured in fractions of a
second, remains fairly constant over the entire range
of speed.
WAj'/e all forms of automatic advaiiftft are eatable

IGNITION TIMING 155

of providing an ample range of advance and retard
for the proper operation of the engine, it is custom-
ary to fit the ignition devices having such automatic
advance with a toianual or hand operated advance and
retard lever also. This manual advance may be used
in the ordinary way by the operator or it may be set
in the position found best for the engine operation
under any given conditions or on any particular day,
then allowed to remain there until weather, tem-
perature or fuel conditions change and make a new
position of the manual advance desirable.

CHAPTER Vn

BATTERY IGNITION SYSTEMS-

DELCO

Two distinct types of breaker mechanism have
been used with the equipment made by the Dayton
Engineering Laboratories, one operating on the open
circuit principle and the other as a closed circuit
type. The first, or open circuit, system was generally

Figrure 61.-^-Open Circuit Type of Breaker (Delco).

used up to and induding the year 1915. Of this type
there are three mechanieal variations.

On the earlier installations used in connection with
electrie lighting and engine starting systems two
Jkreakeiv, were supplied, one for the dynamo and

156

BATTERY SYSTEMS 167

storage battery current source and the other for
the auxiliary dry cells. ^ The storage battery breaker
is of the two wire or insulated type, having no parts
grounded, and therefore being provided with two
terminals. The dry cell breaker is of the more usual
grounded type with but a single outside terminal.
The principle of construction of either of these
breakers as well as all other Delco units of this open
circuit type is shown in Figure 61.

On the installations which followed the one just
described the two breakers were combined into one
mechanism which functions for either sourcie of cur-
rent. This device is shown in Figure 62, the prin-
ciple of action being like the breaker in Figure 61,
but being mechanically changed in having two arms
and two sets of contacts operating from the same
cam. One of the arms and sets of contacts breaks
the circuit for the storage battery ignition while the
other acts for the dry cells. Of the three terminals
one is for storage battery current, one for dry cell
current and the third is a common return lead for
either source.

The last installations making use of the open cir-
cuit principle used a single breaker, much like the
first dry cell mechanism, with a single outside ter-
minal and provided connections which allowed this
one breaker to act with either storage battery or
dry cell current.

On these breakers as manufactured during 1912
and 1913 the small cam is permanently attached to
its shaft with a steel pin and in order to change the
timing the driving shaft must be lifted out and set
one or more teeth ahead or ba^k^«:c^. \s^*Cw^>st'^€j«^-

158 AUTOMOBILE IGNITION

ers made from 1914 on, the cam is mounted on a
small shaft whose lower end is slotted to allow espaii>
sion. Through this shaft passes a screw whicll
expands the lower end of the shaft. This assembly
fits into a cylindrical hole in the breaker shaft
proper. With the screw tightened, the cam is held
securely in place, while loosening the screw allows
the timing to be changed without any alteration in
the driving mechanism for the breaker shaft This

Figure 62. — Dual Form of Battery Breaker (Delco).

construction may be noted in the upper iUnstration
of Figure 58.

The closed circuit breaker used since 1916 is shown
in Figure 63. This device consists of a straight arm
fitted with a small bumper against which the lobes
of the cam strike when the contacts are to be sepa-
rated. The contacts are normally held closed by a
long flat spring attached to the pivoted end of the
arm. The fixed contact is adjustable by turning its
screw and the adjustment is maintained by a lock

BATTERY SYSTEMS 159

nnt. The position of the cam may be altered by
loosening the screw in its center, the construction
being the same as that described for the later con-
structions of the open circuit breakers.

Even though the lightness of parts and accuracy
of workmanship allows breakers of this type to oper-
ate with exceeding rapidity, the number of spa^s

Flffure 63. — Closed Circuit Type of Breaker (DalOo>.

required by some of the eight and twelve cylinder
engines has led to several modifications by which
these conditions may be met with greater facility.
Some breakers are constructed with two arms oper-
ating on one cam as shown in Figure 21, one arm
providing one half the breaks in the primary circuit
and consequently one half the number of sparks,
while the other arm does the remainder. In other
cases two complete and separate breakers and dis-

160 AUTOMOBI1.B IGNITION

tributors have been installed, each caring for one
^ half the number of cylinders on the engine. .

Distributors. — The Delco distributor is of the wipe
contact type having a contact connected with the
high tension coil winding and a rotor which connects
this central contact with those whose wires lead to
the spark plugs of the cylinders. The rotor makes
contact with the spark plug terminal segments
through a metallic button on which a very light ten-
sion is maintained by a coil spring under the button.

About once a month the insulating head of the

FIgrure 64. — Distributor Rotor with Grounding: Button

(Delco).

distributor, together with its terminals and segments,
should be removed and cleaned with a cloth slightly
moistened with kerosene. Lack of lubrication may
have caused the track followed by the rotor button
to have become rough or blackened. If this condi-
tion should be found the track should be cleaned
with the finest grade of emery cloth, not with sand-
paper. The track should be found in a highly pol-
ished condition and when in this state it should never
be touched. After placing the track in good condi-

BATTERY SYSTEMS 1«1

tion a very small amount of vaseline should be
applied with a cloth.

In the center of the head is a small spring plunger
which makes contact with the inner end of the rotor.
The spring which gives pressure to this plunger
should act freely and the lower end of the plunger
should be clean to allow good electrical contact with
the rotor. Care should be used in replacing the dis-
tributor head not to bind any of the button or'
plunger springs in any way.

It should be noted that the rotor button requires
very little tension to make good contact on the dis-
tributor head. Should the button have been pulled
out of place at any time this tension may have been
increased sufficiently to cause harm. Should too
great spring tension have caused the rotor button
head to become scored or rough it should be
smoothed first with very fine emery cloth, then with
crocus cloth and finished by buffing on leather. If
the spring tension is too strong the spring may be
removed and the coils compressed with small pliers.

The rotors fitted to the 1912, 1913 and some 1914
systems carry two buttons as shown in Figure 64.
One of these buttons is for the purpose of carrying
the high tension current to the spark plug in the
cylinder about to fire, while the other button, fol-
lowing the first one, is for the purpose of grounding
the spark plug wire for the cylinder next to fire.
Due' to induction between the high tension wires
which parallel each other through the carrying tubes,
it is possible that a spark might be produced in the
cylinder next to fire when its piston was just start-
ing up on the compression stroke ^xA SX. \^ \»^ ^^^ixv^^st

162 AUTOMOBILE IGNITION

this spark harmless that the additional button was
provided.

The construction of a Delco ignition head for a
twelve cylinder engine is shown in Figure 65.

Condenser. — It is of course necessary to provide a
condenser for each point at which the primary cur-
rent is broken and in following this rule Delco sys-
tems have been provided with one, two or three
separate condensers, depending on the type of instal-
lation. The early installations having two independ-
ent tinaers or breakers were provided with a con-
denser attached to each breaker and these same sys-
tems also had a third condenser fitted to the ignition
relay which is a vibrator of special form.

Those systems which use one breaker with two sets
of contacts for the two current sources have a single
condenser for the two sets, but these systems were
also equipped with an ignition relay which had its
own condenser. The equipment of twelve cylinder
engines having two separate breakers also includes
separate condensers for each breaker. Those sys-
tems having but one breaker with a single arm and
without an ignition relay carry but the one con-
denser for the one breaker.

Condensers have been mounted close to the breaker
contacts, in many cases in the cover over the centri-
fugal advance mechanism for the spark timing or
for the dynamo regulation. In many of the later
cars the condenser is carried inside the coil covering
as shown in Figure 36 or mounted on the coil case.

Coils. — The ignition coils are of the conventional

type having a primary winding of a few turns of

comparatively coarse wire and a secondary or high

tension winding of a great ma\iy \A3Lni«» of very fine

BATTBBT SYSTEMS

164 AUTOMOBILE IGNITION

wire. A single coil has been fitted except in the early
installations having separate breakers for storage
battery and dry cell current and in some of the recent
equipments having separate breakers and dis-
tributors for twelve cylinder engines. '

Resistance VnU. — T^iis is a coil consisting of a
number of turns of iron wire which may be mounted
on the dash, on the coil or on the breaker and dis-
tributor case. Its purpose is to insure against waste
of battery current and damage to the coil and to the
timer contacts should the ignition switch be left on
and also to obtain a more nearly uniform current
through the primary winding of the ignition coil
with varying speeds of the engine and dynamo.

The resistance unit is always so connected in the
ignition circuit that all current passing through the
breaker contacts which control the storage battery
ignition shall also pass through this unit. Under
ordinary conditions the wire remains cool and offers
but little resistance to the passage of current. How-
ever, if for any reason the primary current should
flow uninterruptedly for some time, this passage of
current through the iron wire would heat it. Heat
increases the resistance of iron wire many fold after
passing a certain critical temperature and this
increase in resistance prevents all except a very
little current from passing.

With the later types of closed circuit systems it
is evident that the time during which the primary
current flows is much greater at low engine speeds
than at high ones, the relative difference being
greater with such a system than with the open cir-
euj't type. As applied to this closed circuit type the

BATTERY SYSTEMS 165

resistance unit, therefore, performs an important
function.

The ignition resistance unit should always be in
circuit and if there is any doubt it should be tested..
A simple test may be made by turning on the igni-
tion switch with the engine idle and with the breaker
contacts together. If the resistance is doing its
proper work the iron wire will soon become heated,
but should it remain cool under these conditions the
connections and other parts of the circuit should be
examined and checked. If the resistance coil itself
is burned out a new one should be immediately
secured and installed.

Current Source, — The source of current for normal
running is either the storage battery or the dynamo.
At engine speeds so low as to prevent the voltage of
the dynamo from rising above that of the battery,
the ignition current will be drawn wholly from the
storage battery. If the amperage generated by the
dynamo is less than the amperage used for ignition,
the deficiency will be made up from the battery and
all the dynamo current will be used for ignition also.
If the dynamo is generating more current than
required for ignition then all of the ignition current
will be supplied by the dynamo and the surplus gen-
erated will go to the battery or current consuming
devices. Ignition using the dynamo or storage bat--
tery as a current source is called *'M,'' *'Mag'' or
magneto type ignition in Delco systems. The auxil-
iary current source consists of five or six dry cells
and is known as the **B,'' ''Bat'* or battery ignition.

Ignition Relay. — This device is one peculiar to
Delco systems made durmg Wife ^^^x^ I^wsl^SSTs^ •vs^

106 AUTOf&lOBILB IGNITION

1914 inclusive. The construction and electrical con-
nections are shown in Figure 66.

The ignition relay is always connected in the
primary circuit having the auxiliary dry cells as cur-
rent source and is never connected with the dynamo
or storage battery ignition system. The action is
to immediately bfoak the primary circuit as soon as it
is completed through the breaker contacts, thereby
causing a spark to take place as soon as the breaker
contacts close and establish the circuit, regardless
of the time at which they open, which would, in
ordinary constructions cause the spark. This action,
which makes it impossible to maintain a current'
flow but for an instant through the relay and coil,
places this parti-^ular type of Delco ignition system
in the class of true open circuit devices in which !it
is impossible to maintain a flow of primary current
for any length of time regardless of the switch or
breaker cam petition. There is, however, a small cur-
rent flow through one winding of the relay.

Reference to Figure 66 will make clear the follow-
ing description of the relay's action. Magnet A
attracts armature B when the current flow passes
through the breaker contacts. This armature, when
attracted by the magnet, forces the contacts C apart
and these contacts break the primary circuit. There
are two windings on magnet A, one of comparatively
coarse wire so connected that current ceases to flow
through it when the contacts C separate. The other
winding around magnet A is of fine wire so con-
nected that current through this fine winding passes
around contacts like a shunt. The current that con-
tioi^eG fe flow through this fine winding even after

BATTERY STSTEMS 167

contacts C have opened causes the magnet A to hold
the annature B and keep contacts C apart.

If this second fine wire coil were not effective the
contacts C would open and close like an ordinary
vibrator, which the device would then in effect
become. This vibration would give a stream of
sparks in place of the single spark caused by open-
ing the contacts as described. This stream of sparks
is desirable in starting and in many installations pro-

Flsure 6E. — D«lci> Isnltloi

vision is made for opening the circuit through the
fine wire winding, thus rendering this part of the
magnet ineffective and allowing contacts C to fur-
nish a true vibrating spark aa long as the breaker
contacts remain closed.

The only adjustment for the relay is at the pole-
piece E. This adjustment regulates the distance
between armature and magnet poV* a;w^, aSso "fioR. «*^

168 AUTOMOBILE IGNITION

between contacts C. Turning the notched head
clockwise, looking from the top, increases the gap,
while anti-clockwise rotation closes the gap. This
adjustment should be such that the distance between
contacts C when armature B is pressed down is
about equal to the thickness of a shee^t of writing
paper. The most economical adjustment may be
made by starting the engine, then turning the
notched head anti-clockwise until the engine stops.
Then turn the notched head four or five notches in a
clockwise direction. Should the relay vibrate when
the **B'' switch is closed and without the starting
button in use it indicates that the circuit through
the fine wire coil on the magnet is open and this cir-
cuit should be traced. The space I should be kept
free from dirt.

Switches, — The several principles on which Delco
ignition switches have been constructed are shown in
Figure 67. The type shown at A is of the simple
kick lever style and serves to complete one of two
circuits depending on which way the lever is swung.
With the left hand contacts closed the dry cell source
of current is in use and the ignition relay already
described is used in producing the spark. With the
right hand contacts closed the storage battery or
dynamo is in use in connection with the ignition coil,
but without the relay.

The construction as shown incorporates with the
switch a '* starting button" which, when pressed,
opens the circuit through the fine wire coil of the
relay magnet and allows the relay to deliver a stream
of sparks with vibrating action. Switches of this
type, with or without the stax\.mg button, were used

BATTERY SYSTEMS 109

during the years up to and including 1912 and on
some cars during 1914.

The switch construction shown at B is the one
generally found on installations of the year 1913.
On a circular plate attached to the dash or instru-
-ment board are four push buttons. Looking from
the driver's side the button at the left closes the dry
cell ignition circuit and allows the ignition relay to
deliver a single spark for each closing of the breaker
contacts. This is known as the * * B ' ' button. At the
right is the "M" button, which when pressed, closes
the circuit for the storage battery and dynamo igni-
tion. The lower button is marked ''STAET'' and
opens the fine wire winding circuit of the relay mag-
net while throwing the dry cells into .the ignition
coil and relay circuit so that a vibrating spark is
produced which is suitable for starting the engine.
The top button is marked "OFF'' and is for the
purpose of releasing any of the three other buttons
which have been previously pressed, thus stopping
whichever source and type of ignition is in use. With
this top button is incorporated a lock which prevents
any of the ignition buttons from being pressed in
and thereby prevents the engine from being started
until the key is inserted and turned. A peculiar
characteristic of this switch is the construction
which causes any button which may be already
pressed in to be released and open its corresponding
circuit when one of the other buttons is pressed. The
figure shows the switch connections and contacts
as they would be seen from the back or engine side
of the dash.

The third type of switch is shown ypl FV^sis^^ ^1 ^e&*

170 AUTOMOBILE IGNITION

C and combines the functions of ignition and light-
ing. This construction provides several contact seg-
ments over which one or more contact fingers or-
arms are arranged to travel with movement of a
lever or button accessible to the driver. By suitable
arrangements of the segments with their connections
to the outside wiring and thereby to the dry cells,
storage battery, ignition relay, coil and other parts
of the sytsem ; various sources of ignition and types
of ignition are brought into use. This style of switch
was first used in 1914.

I the construction shown at C a starting button
is built into the combination switch housing. This
button, as in preceding types, causes the ignition
relay to produce a stream of sparks by making the
fine wire magnet winding inoperative. This particu-
lar construction also allows the starting button to
assist in the use of the electric starter for the engine
by sending a small current through the starting
motor so that the armature and the gears meshing
with the flywheel gear are caused to revolve slowly,
thereby rendering engagement of the gears more ^
easy. At D is shown a construction following this-
same principle and which was used in 1916. This
method of construction lends itself well to following
out the individual ideas of car designers as to cer-
tain desired combinations of lighting and has there-
fore been used in large numbers and with many slight
differences in details of construction and lighting or
ignition arrangements secured.

At E is shown a combination ignition and lighting
switch, which with some slight changes and modi-
£cationB was very commonly used in Delco equip-

BATTBRT SYSTEMS

172

AUTOMOBILE IGNITION

ment starting with the year 1915. This type of
switch, in the constructions first used, consists of
five push and pull buttons; the two at the driver's
right being used for ignition while the three toward
the left are for lighting. In the construction shown
the button at the driver's extreme right (and at the
left of the illustration showing the back view) com-

9TCRACC
aATrcRV

oisrnieuTo/^

Figure 68. — Igrnition Circuits Used with Delco

Systems.

'Junior"

pletes the ignition circuit from the storage battery
and dynamo to the ignition coil. The button next
to the right hand one completes the dry cell igni-
tion circuit.

It will be noted that each of the ignition plungers

will complete two sets of contacts or two circuits

when pulled out and thereby closed. The larger pair

of contacts complete the ignition circuit, while the

BATTERY SYSTEMS

173

«0

^^ NO

Moo
I

174 AUTOMOBILE IGNITION

smaller pair establish the circuit between the dynamo
and storage battery. With the engine idle this com-
pletion of a circuit from the battery to the dynamo,
which in earlier equipments, also acted as a starting
motor, causes the armature of this machine to re-
volve and allows easy meshing of the starting gears.
With the engine started and running at a speed suf-
ficient to allow the dynamo to charge the storage
battery, these contacts on the ignition switches allow
the charging current to flow from dynamo to
battery.

A modification of this push and pull button switch
first used in 1916 is shown at F. This construction
has but four buttons, one for ignition and three for
lighting. With this style of switch no dry cells
are used, the storage battery and dynamo being
depended on as the sole source of current. As in
the construction just described, the ignition switch
also completes the charging circuit through an addi-
tional contact, this flow of current between battery
and dynamo causing the same effects as with the
switch having five buttons. In some cases the ignition
plungers carry contacts for dynamo fields.

Wiring, — Most of the Delco systems up to and
including the year 1913 were of the two wire or
insulated return type. In these systems both the
• positive and negative sides of the circuit were car-
' ried through insulated copper wires. Since 1914
nearly all Delco installations have been of the one
wire or groimd return type in which, as a general
rule, the negative side of the battery and the negative
side of all circuits is grounded, that is, connected
¥FiYl2 the metallic framework of the car so that the

BATTERY SYSTEMS

175

*^
oq

Wo
^3

OS:

on
goq

2w
• c

r»-

O
P

►*•

►*•
O

176

AUTOMOBIL.E IGNITION

positive current is carried without the use of insu-
lated wires.

Typical ignition circuits as found in connection
with the kick lever switch are shown in Figure 68,
as used with the round four button switch in Figure
69, as used with the five push and pull button switch
in Figure 70, with the four push and pull button

^4Swf<r/ss<

-at

f/j Aimiir/iafSuv^

/AN /An

*■

/^MrfC^

o^^oe^aei^

COtL

Figrure 71.— Ignition Circuits Uslngr Four-Button Combina-
tion Switch (Delco 1916-1918).

switch in Figure 71 and with the rotary or segment
switches in Figure 72.

Spark Advance. — ^IJp to and including 1912, Delco
equipment was provided with only hand or manual
advance and retard means for controlling the spark.
On cars equiped with two separate breakers and dis-
tributors these breakers were interconnected so that
Aotli were advanced and retarded at the same time

BATTERY SYSTEMS
YCett.3

178 AUTOMOBEL.B IGNITION

from a single control lever on the steering wheel.
With 1913 equipments the dry cell ignition was pro-
vided with hand advance while the storage battery
ignition had the hand advance and also an auto-
matic advancing mechanisni as described in Chapter
Six under Automatic Advance. This same type of
automatic advance mechanism was thereafter used
for both sources of ignition until the year 1916, when
a later type, also described in Chapter Six, was intro-
duced.

ATWATER KENT (OPEN CIRCUIT) SYSTEM

Breaker. — The underlying principle and the con-
struction which chiefly distinguishes the Atwater
Kent open circuit ignition equipment from all other
makes and types is found in the breaker, which is
of decidedly novel construction. The operation of
this device may be understood by reference to Fig-
ure 73, which shows the first used mechanism of
this make. While certain modifications have been
made siace this particular type was first introduced,
the principle of action remains unchanged and is
more easily understood by describing the first method
of building than those found later. The later modi-
fications will be described in their proper places later
in this chapter.

Operating the breaker is a shaft driven at cam-
shaft or one-half engine speed, and this shaft has
notches as there are cylinders. A long arm, which
is variously called a lifter, pawl or striker, is piv-
oted at one end and has its other hooked end rest-
jn^ against the notched shaft. Attached to this

BATTERY SYSTEMS 179

arm is a small coiled spring which acts to pull the
anu back from the shaft.
As the shaft rotates, the hooked end of the arm

t Breaker System.

is caught by the notches in the shaft and -when
engaged with a notch the arm. va ^NiSV*,^ \si. ■\!e«.

180 AUTOMOBILE IGNITION

. direction of the shaft's rotation. It will be noted
from the illustration that after the arm has been
pulled forward a certain distance the hook will
no longer remaiit in the notch and the arm is then
released and very quickly pulled back to its posi-
tion of rest by the coiled spring.

In returning to its normal position the arm rides
over the rounded or smooth portion of the shaft,
which is between the notches, and in so doing it
strikes a projection on a second arm, which car-
ries one of the breaker contacts, throwing the con-
tact arm a distance sufficient to close the contacts
which are in the coil circuit. The return of the
striker arm under the action of its spring is exceed-
ingly rapid and the contact is made and broken so
quickly that the eye cannot follow the movement, yet
the coil is properly energized.

It will be seen that the duration of the contact
is independent of engine speed or of the speed of
rotation of the notched shaft because the contact is
not made when the striker arm is pulled forward
by the shaft, but on the return, which is actuated
by the spring. The action of the spring, after the
hooked end of the striker arm is released, is always
the same whether the shaft be rotated slowly or
fast and the intensity of the spark, which depends
to a great extent on the time of contact between
the breaker points, is uniform over the entire range
of engine crankshaft speed. The length of contact
and the strength of the spark is in all ways inde-
pendent of engine speed except as the voltage of
a storage battery also used in the electric lighting

system might raise or lower a.a \\i^ Qc^^tclq «^^^d

BATTERY SYSTEMS 181

and voltage became greater or less with change of
speed. ^

This type of Atwater Kent equipment is of the
true open circuit construction because there could
be no flow of current unless the engine crankshaft
were revolving, even though the switch might be
closed. With the engine idle the striker arm is
always in its position of rest, and in this position
the arm carrying the contact is not being acted
upon. Therefore, with the ignition switch closed,
the ignition coil circuit and battery circuit is still
open at the breaker contacts and cannot be closed
except by allowing the shaft to pull the striker far
enough forward for the notch to release the hook.

The Atwater Kent open circuit breaker will pro-
duce a spark only when running in one given direc-
tion, clockwise or anti-clockwise, depending on
which way the notches are facing around the shaft.
The shaft must run in the direction that will carry
the striker arm forward and let its spring pull it
back. Rotation in the reverse direction will have no
effect whatever so far as closing the breaker con-
tacts and causing a spark is concerned.

The construction of a later type of Atwater Kent
open circuit breaker is shown in Figure 74. The
principal difference between this and the type al-
ready shown and described is that an intermediate
latch is interposed between the striker arm and the
contact carrying arm, this change allowing the use
of smaller and lighter moving parts.

In the newer type the arm is caught as before
on one of the notches in the shaft and pulled for-
ward. In this movement tlv^ ^l\\k^x ^xxss. ^^^si.^^^

autdmobh^e ignition

by the latch. When the hooked end of the arm is
released the V shaped back of the arm strikes the
point of the rocking latch and the latter in turn
strikes the contact carrying spring, bringing the

PlKure 74.— Operation o( Atwater Kent Open Circuit Breaker.

Top: Contact Open. Lower Ijeft: Contact SUM Open.

Lower Center; Contacta Closed. Lower

Right; Contact Broken.

contacts momentarily together and allowing them
almost instantly to separate.

Adjvstment. — The only adjustable featnre of the
Atwater Kent sj'stem is the distance or gap between

BATTERY SYSTEMS 18^

the contact points in the breaker when the engine
is at rest. The normal gap between these points is
from ten to twelve-thousandths of an inch, never
less than this, and under no conditions should the
contacts touch each other with the engine idle. The
spark may be made hotter by decreasing the gap and
current may be slightly economized by increasing it.

The Atwater Kent system was originally designed
to operate with a set of dry cells as its current
source. In that case it replaced the old time vibrat-
ing coil and batteries and the principal aim was
certainty of operation and economy of current.
With dry cells in use the proper gap between the
contact points is about 1/32 inch. With a storage
battery this distance may be slightly reduced. As
the batteries become weaker with use, the gap should
be reduced by turning the adjusting screw in from
one-quarter to one-half turn, or until a satisfactoiy
spark is obtained.

With the lighting dynamo and storage battery as
the source of current the gap of ten to twelve-thou-
sandths of an inch is correct under all conditions.
The contacts on all of the later types of this equip-
inent are made from tungsten, and when the breaker
is operating properly, small particles of this metal
will be carried from one contact to the other, some-
times forming a roughness and a dark gray color
on their surfaces. This roughness does not in any
way affect the proper working of the points becausQ
of the fact that the rough surfaces fit perfectly into
each other. However, when it becomes necessary
to take up the distance between these points due to
natural wear, it is usually ^Am^IeXfc V^ ^^xsl^^^ *^i«^

184 AUTOMOBILE IGNITION

contacts from the breaker and with a very fine new
file dress down the high spots. This eliminates the
possibility of opposite high points touching each
other with the new setting and with the engine at
rest.

The tungsten contacts are very hard to file and
'it is necessary to remove but a very small amount
of metal. Although the contacts may be found
decidedly rough, if the ignition spark is good it is
probable that they are in perfect working condition
and no change should be made.

The adjustment of the contact point gap on the
earlier types of equipment is obtained by mounting
the fixed contact on the end of a screw which passes
through a threaded opening in a supporting post.
Turning this screw one way or the other lessens
or increases the gap.

On the next type both contacts are carried by
steel springs. The adjusting screw bears against thd
back of the spring that carries the fixed contact,
and by turning the screw the fiat spring with its
contact is moved closer to, or farther from, the mov-
able contact so that the gap is altered. With this
method of adjustment the contact point itself is
not turned, but remains in the same relative position
on its spring regardless of the distance between the
points.

"With the types of equipment being furnished at
present the adjusting screw again carries the fixed
contact point and is provided with a number of
thin shims under its head. When, through wear of
the contacts, the gap becomes too great the screw
IS removed from the post through which it passes

BATTERY STSTEM3 18B

and a sufficient number of shims or one shim of suf-
ficient thickness may be removed, which will allow the
correct distance to be obtained. With the shim or
shims removed the screw is again replaced and set
down tight.

In making adjustments no change should ever
be made in the tension or shape of any spring and
no change should be made in the shape of any of
the parts comprising the breaker.

Distributor. — The Atwater Kent distributors are
of the jutap spark type in which there is a slight

Figure

Space between the rotor and the small pins from
which connection is made with the spark plug wires.
This construction is shown in Figure 75. The spark
jumps across this space while the device is in opera-
tion. The rotor consists of an insulating block car-
rying a contact segment on its circumference. This •
block fits over the top of the revolving shaft and
because the driving slot and kt^ m^ 'Sti.^i!is>j:3 vi"&s*!.

186 AUTOMOBILE IGNITION

from center it is impossible to place the rotor on
the shaft in other than the correct position. The
distributor cap is held in place by steel springs, and
due to an irregular arrangement of the guide pius
and slots it is also impossible to replace the cap in
any position other than its original settrug.

Coil and Condenser, — The coil is of the usual type
having a heavy wire primary winding of few turns
and a secondary fine wire wiuding of many turns.
Atwater Kent coils for use with the open circuit
systems are so designed that they deliver a high
tension current capable of producing a hot spark
with a very slight flow of primary battery current,
f his is necessary because of the short duration of
the contact in the breaker during which the coil
must build up sufficiently to cause a spark upon the
break occurring.

With some of the types of equipment the con-
denser is carried in the coil box, while with other
types the condenser is mounted in the breaker and
close to the contact points themselves. Coils are
built for mounting on the dash, under the hood, or
on a base attached to the engiae and which also
carries the breaker and distributor.

Switches. — With the first used equipments the
jswitch was carried on the coil box and consisted
of a small brass lever with a hard rubber button
handle, the whole hinging on a post from which
the lever could be removed when turned to a cer-
tain position. At one side of the switch handle was
a starting button which closed and opened the bat-
tery circuit through the coil, thus producing a spark
la whichever cyiinder was ready to fire and jvhose

BATTERY SYSTEMS 187

spark plug wire was in connection with the coil
through the distributor.

A kicji switch was later used and mounted either
on the coil or separately on the dash when the coil
itself was carried under the hood. The lever on
this switch is not removable, but at one side of the
switch housing is carried a remorable key, which
when taken out .prevented closing of the circuit.
This separate switch is 'also .provided with a start-
ing button.

In .order to prevent the deposit of a surplus of
metal on one of the breaker contact points, due to
maintaining the flow of current always in one direc-
tion, as was the case with earlier outfits, a revers-
ing switch of a rotary type has now been provided.
The handle is always turned to the right, either
to turn the ignition on or off. In one position the
flow of current passes from the fixed to the movable
contact in the breaker, while the next time the
switch comes to the **0N'* position the flow reverses
and is from the movable to the fixed contact. The
,result is that metal is first carried from the fixed
to the movable contact and is then carried back.
Various other types of switches are used with
Atwater Kent systems, these being provided by the
car manufacturers and varying with the make and
model of car. «

Wiring. — In Figure 76 is shown the wiring for
the old style system for two cylinder engines with
the small lever switch carried on the coil box, also
for this same type of switch and coil when used
with a distributor in connection with an engine of
more than two cylinders. Wiring tot \}w^\^<^^ v^^^^

188 ' AUTOJJOBILE IGNITION

with a reversing or a kick switch, mounted either
on the coil box or separately, is shown in Figure 77.
AH of the types shown in Figures 76 and 77 have

FlEure IS. — Wiring of Older Types of Atwater Kent Opes

Circuit Equipment. Top: Two Cylinder Engine

Type. Bottom: Distributor Type.

one side of the circuit grounded to the metal of
tie engine and car, although the battery itself is

BATTERY SYSTEMS 189

not directly grounded, but is connected first with
the coil or switch.

In case the lighting battery is used for ignition,
two wires froQi the ignition system, as shown in the
diagrams, should run directly to the battery and
should not be connected in on any branch lines of
the lighting, starting or horn circuits. The two
terminals of the breaker should be connected with
the terminals on the coil by means of a length of
twisted duplex or double conductor cable. Under
no conditions should separate lengths of wire be
used between breaker and coil.

Spark Advance, — The several types of breaker
construction are made either for hand advance and
retard of the spark or for automatic advance. The
automatic advance mechanism is described in Chap^
ter Six. The types having automatic advance mech-
anism carry the device in the same housing with the
breaker and distributor and immediately below the
breaker. These types may be installed to elimiaate
the spark control lever entirely by clamping the
breaker housing rigidly in one position. In this
case provision is made for a small amount of move-
ment in the clamping device for purposes of timing
the spark for idling and starting the engine. In
case the spark control lever is used with one of
the types incorporating automatic 'advance it is
used for what might practically be called adjust-
ment only and the connections between the hand
lever and the breaker housing are so proportioned
that the breaker has a total range of movement not
exceeding one-quarter to one-half inch for the entire
travel of the hand lever.

AUTOMOBII^ lONITION

Timing. — The Atwater Kent equipment construct-
ed for hand or manual advance only, types C, F and
E, is timed as follows:

Figure 77. — Wiring of

„ .. Kent Open Circuit Equip-
Left: With Separate ReversltiK Switch.
RIeht: With Switch On.CoW Bo^.

BATTERY SYSTEMS 191

Crank the engine until the piston of the cylinder
bein^ worked upon, usually number 1, is at top
dead center between the compression and power
strokes. The breaker should be placed on its driv-
ing shaft with the advance rod connected to the
lug on the breaker housing and with the hand lever
on the steering wheel within one or one and one-
half inches of full retard position. With the piston
in the position described and with the breaker shaft
loose on its driving shaft, turn the breaker shaft
forward, or in the direction that it is driven with
the engine running, until a click is heard. This
turning must be done slowly and the breaker shaft
must not be moved aft6r the click is heard. Ipi this
position set the breaker shaft on the driving shaft
by tightening the driving connection.

In timing the Atwater Kent systems having auto-
matic advance, types K, K2 and K3, follow the same
procedure as above except that in turning while
listening for the click, turn the whole breaker and
distributor head rather than the breaker shaft, and
turn it backward or in the direction the reverse
of that in which the shaft is driven by the engine.
This of course has the same effect as turning the
shaft alone in a forward direction, but because of
the advance mechanism, the result is more easily
obtained in this way than by turning the shaft.

ATWATER KENT (CLOSED CHICUIT) SYSTEM

Closed circuit Atwater Kent equipment is made
either with or without the automatic spark advance
mechanism. These types differ frouL ti^a^^ \^i^ ^^s^

IBS AUTDMOBIL.E IGNITION

scribed in that the breaker contacts are normally
closed, in place of normf^y open, and are opened
by a cam when a spark is required. The coustnic-
tion of the breaker is shown in Figure 78. It will
be noted that the cam operates against the contact
arm at the outer end of the arm and that the con-
tact is carried between the fulcrum and the cam

Figure 78. — Closed

Type of Breaker (Atwater Kent).

bumper rather than at one end of the arm as is
generally the practice. The contact carrying arm
is extremely light in weight and is hinged on a small
flat spring rather than any form of pivot or bearing.
Condenser. — The condenser as shown in Figure 79
is carried on the breaker base and close to the .
breaker contacts. The body of the condenser is of
very small outside dimensions, a result which is
possible because of its being located close to tbe

BATTERY SYSTEMS 193

contacts. The body rests in a recess in the base
and is protected by a screwed on cover which car-
ries the terminals and the arm to which is fastened
the adjustable contact point. Dae to this mount-
JBg of the adjustable contact the gap between the

breaker points should always be checked after the
condenser has been examined for any reason. The
leaves of the condenser end in two flat copper termi-
nals which are clamped under th.« wst^w^ V«s.^q.

194 AUTOMOBIIJB IGNITION

hold the cover in place so that one terminal is in
contact with the metal surface of the breaker base
and the other terminal in contact with the condenser
<50ver which carries one of the contacts.

Adjustment. — The contacts are made from tung-
sten and may appear rough and of dark gray color
while in perfect operating condition. This rough-
ness and color in no way affects the serviceability
of the contacts, this feature having already been
explained in describing the open circuit system. It
should not be necessary to dress these points, but
they may be cleaned by carefully scraping with a
penknife. The normal gap between the contact
points when they are f^lly open is six-thousandths
of an inch. Provision for changing the size of this
gap is made by carrying one* contact on a slotted
bar, this bar being held in place by a clamping
screw. With this clamping screw loosened the bar
may be moved toward or away from the contact
on the arm until the proper setting is obtained.
The adjustable contact is thus moved in a straight
line while the gap is changed and the contact points
do not change their positions relative to each other.

Distributor. — The distributor is of the jump spark
type and of the same construction as found with
the open circuit systems. Each spark plug wire
terminates in an electrode which passes through the
distributor cap. The segment on the rotor block
just clears these electrodes and the high tension cur-
rent passes across this slight gap on its way ta the
spark plug line.

Coil. — The coils used with the closed circuit sys-
tems are of the' usual construction and are sealed

- BATTERY SYSTEMS 195

into a cylindrical tube. On top of the tube and
inside of a ventilated chamber is a length of resist-
ance wire which performs the same functions as^
d'oes any such unit in an ignition system; namely^
to protect the coil and contacts against an excessive
flow of current at low engine speeds or in case the
ignition switch is left turned on with the engine
at rest.

Wiring. — The appearance of the external wiring^
and all of the internal connections for the closed
circuit systems are shown in Figure 80. The switch
may be of the reversing type already described or
may be of any suitable construction as furnished by
the car maker. The method of fastening the spark
plug wires to the distributor terminals has been a
characteristic of Atwater Kent construction for some
time. The distributor wire is bared for a distance
of about V/s inches. The terminal cover is then slid
up over the wire and the bared end of the wire is
passed through the hole in the terminal on top of
the distributor cap. The end of the wire is then
twisted back upon itself to the right so that the
twisted part will not be greater in diameter than
the part with the insulation still on. With the ter-
minal cover screWed back in place the wire will
be securely held. The cover should be screwed in
place with the fingers only and the ends of the
vires should never be soldered to the terminals.

Timing, — ^With the piston of the cylinder being
worked upon at top center between compression and
firing, the breaker should be set to just start open-
ing the contacts. With the breaker in this position
the spark advance lever on the steering ^\^&<^V'^<5s^i5s^

196

AUTOMOBILE IGNITION

be almost fully retarded. The movement of the
control levers and rods should be sufficient to rotate
the breaker from seven-eighths to one inch for the

rropuiG

OROUNO

GROUND

REGULATINO
RCdiSTANCe

Figure 80. — ^Wiring and Internal Circuits of Closed Circuit

Ignition System (Atwater Kent).

full range of spark timing.

If the equipment includes the automatic advance
device, not more than a total movement of five-

BATTERY SYSTEMS 197

eighths to three-quarters of an inch should be al-
lowed at the breaker for full travel of the hand
advance lever. In other respects the .timing is done
in the same way as for th^ hand advance system
bearing in mind that it is better to move the entire
breaker mechanism backward :than to move the
breaker cam shaft forward.

Any of these systems may be accurately timed by
completing all the electrical connections and then^
with the spark plugs resting on top of the cylin-
ders, move the breaker slowly until the contacts
open and the spark occurs, while the piston remains
at top center as set.

REMY VERTICAL IGNITION SYSTEM

The Remy battery ignition system, which has been
generally used since 1915, comprises a closed cir-
cuit breaker above which is carried the distribu-
tor, and a separate coil and switch. This breaker
is shown in Figure 81. The arm is pivoted at one
end, carries one of the contact points at the other
end, and near the center is' fitted with a fibre bumper
against which the lobes of the cam strike in caus-
ing the contacts to separate. The breaker contacts
are made of iridium-platinum, tungsten or silver ac-
cording to the installation with which used. A small
flat buffer spring is mounted so that with a too
wide opening of the contacts the end of the contact
carrying arm strikes against this spring with some
force. With the contacts fully separated in normal
action the end of the arm just strikes this si^riiL^
and a quick return to tke cVos^Qi ^ci^\\AskL Sa. ^^^w^-

198 AUTOMOBILE IGNITION

lerated. Missing may occur at high engine speedi
should this spring become bent oiit of shape so that
the arm does not touch it.

For four, six and 'eight cylinder engines the
breaker cam is square, hexagonal or octagonal re-
spectively, having as many points or lobes as there
are cylinders to be fired. Equipment designed for
use with twelve cylinder engines is fitted with a six-
point cam and with two separate arms and sets of
■contacts as shown in Figure S4. These arms are not

fiet exactly opposite each other, but are so placed
that with one set of contacts opening, the other ,
set is just midway between points of opening. One-
half the cylinders are fired by one set of contacts
and the remaining number by the other set, the
hreahers alternating in action.

Adjustment. — Adjustment of the gap or opening
"between the contacts is made by loosening the lock
nut on the adjusting screw which carries one of
the contacts and turning the screw in or out. After
.making an at^'ustment the lock nut should be se-

BATTERY SYSTEMS

199

curely tightened. The points, when at the maximum
opening caused by the cam lobes, should be sepa-
rated by fifteen to twenty-thousandths of an inch.
With the points fully separated the contact carrying
arm should clear the buffer spring by one-fiftieth
of an inch. Before making an adjustment the con*

^NITION SWtTCH iGN/TION COIL ^neS/ST/fNCt

CmCU/T BRtflKOf
\

IGNITION DiSTmBUTOR

STORRGC B/fTT£ffY

SPRRK PLUGS

Figure 82. — Wiring: of Ground Return System with Condenser

in Coil Case (Remy).

dition of the contacts should \)e examined. If the
points are white and have a frosty appearance, they
are in perfect condition, but if found black, very
rough or pitted, they should be filed smooth and
flat with a new fine file. After thus dressing, the
adjustment may be properly maOi^.

200 AUTOMOBILE IGNITION

The best results will be obtained with these Eemy
systems by setting the gap between the spark plug
points between twenty-five and thirty-thousandths
of an inch. If missing occurs with the engine run-
ning idle or pulling lightly the spark plug gap should
be increased, while if there is missing at high speeds
and under heavy pulling at low speed the gap
should be made less.

Distributor. — The distributor is of the jump spark
type having its rotor fitted with a segment which
revolves close to, but does not quite touch, the pins
arranged around the inside of the distributor cap
or head. The center terminal of the distributor is
connected with a small carbon brush on the under
side of the head and this carbon brush maintains
contact with a spring button attached to the seg-
ment on the rotor. The rotor block fits on the driv-
ing shaft in only one position so that wrong replace-
ment cannot be made.

The rotor segment is pointed so that it forms a
gap of approximately % of an inch between it and
the bottom plate which is grounded on the shaft.
This provides a safety gap across which the spark
can discharge in case any of the connections between
distributor and plugs may have become loose or
broken. This safety gap should not be less than
11/32 of an inch, for the spark might then discharge
across it instead of through the spark plug, even
with good connections to and at the plug.

Coil. — The ignition coil is of the type generally
iound, having high and low tension windings of a
great many and a very few turns respectively. The
windings and core are so proportioned that an ef-

BATTBRY BTSTEMS

2(0.

fective spark is obtained with battety voltages as
low as a total of three and one-half for all cells with
the coil designed for a normal pressure of six to
_ seven volts.

ZiKeuir Bue/mcK.

Figare 83.— Wiring

In the GonBtniction generally used the eondenser
Is carried within the coil case ao-i \a swsqs'Si.^ wt-^'i^fc-

202 AUTOMOBILE IGNITION

With certaii;! modifications in construction the con-
denser has been mounted in the case with the dyna-
mo regulator and cut-out or in a separate homing
attached to the dynahio case.

On top of the coil housing and protected by a
metal cover is a small coil of resistance wire which
is designed to prevent excessive flow of battery cur-
rent through the coil windings and across the break-
er contacts should the ignition switch be left turned
on with the engine idle or with a normal battery
voltage tending to cause heavy current flow at low
engine speeds due to the longer time during which
the breaker contacts remain closed. This resistance
coil is connected in series with the primary winding
of the ignition coil.

Wiring, — WitTi some of the Remy installations the
breaker contact on one side of the circuit is ground-
ed to the metal of the base and in this type the
battery and one terminal of the coil are likewise
grounded, forming a one wire or ground return
system. Remy equipment is also made as a com-
pletely insulated system in which the primary cir- '
cuit from the switch, through the breaker and coil
and back to the switch is not grounded at any point.

With the insulated system a reversing type of
switch is used which changes the direction of flow
across the breaker contacts each time the switch is
turned off and then on again. This reversible switch
is made with a ratchet which prevents its being
turned backward, thus insuring that each, time the
ignition circuit is closed the connections have been
properly reversed.
Figures 82 to 87 show the external and internal

BATTEIRY SYSTEMS

203:

wiring connections of a number of Remy installa-
tions making use of the vertical ignition head in
some of the modifications just described. Figure 82:
shows the equipment having a ground return and-
with the condenser carried in the coil housing. The
connection of the resistance coil is shown outside
the coil housing. Figure 83 shows the condenser
carried with the dynamo regulator and cut-out, this-

4. i /oF^

CIRCUIT BREAKER

U**U4**Ut

Figure 84. — Circuits of Twelve Cylinder Battery Ignition:
System with Double Arm Breaker (Remy).

latter type being of the insulated return construc-
tion.

Figure 84 shows the connections and design used
with twelve cylinder engines, this being a ground
return system with the condenser located at the
breaker and with but the one condenser for both
breaker contact points. In Figure 85 is shown the
method of using the six-volt coil and equipment
with a twelve-volt battery divided into two halves-
of three cells and six volts each. From the neutral
terminal of the battery a line runs to the condensAir >
in the coil, then to the \)T^«kk^T, ^xA *Ccl^ -t^^^OTss^s^,

AUTOMOBILE IGNITION

twitch serves to place first one half, then Ihe Other
half of the battery in connection with the pTimai7
winding in the coil. Figure 86 shows the regolar
method of connecting the reversing switch with

the ground return equipment Figure 87 shows an.
installation using a breaker and distributor exactly
like those found on a magneto of conventional pat-
tern but mounted either on a plate (above) or on a
lighting dynamo (below) without the remaining

BATTBHy SYSTEMS 205

parts of' the magneto. ThU last is also an insulated
return system with the condenser in the coil.

Timing. — The great majority of Remy installa-
tions have been made for hand or manual advance
and retard only, but in some few cases a centrifugal
mechanism has been fitted which automatically ad-
vances the spark to correspond with the engine

AiiXiJr

speed. "With automatic advance the position of the
breaker is fixed at the factory and is not subject
to change by the operator.

With this type of Remy apparatus the gears driv-
ing the breaker and distributor shaft may be meshed
without regard to timing of the spark. Adjustment
is then made as follows ; Liiit ^ivft ^■\&'lt&(sAr« (^^-^"sc

•206 AUTOMOBILE IGNITION

off and remove the distributor rotor with the arrow
-on it from the top of the breaker cam shaft. A
lock nut which holds the cam in place will then be
•exposed and this nut should be removed. Now pry
up on the cam itself while rapping it slightly to
loosen it from the shaft over which it passes with
A taper fit.

The piston of the cylinder to be timed should
now be brought to top dead center between com-
pression and firing strokes and the spark advance
lever on the steering wheel moved a slight distance
' -from its fully retarded position with all control rods
And connections in place between the hand lever
and the breaker boss. With the piston in this posi-
tion move the cam around on the tapered shaft and
in the direction that it rotates when driven by the
engine until the breaker contacts are just about
to separate. Observe the position that will now be
taken by the distributor rotor segment when re-
placed on the shaft and see that it is in position to
pass the high tension current to the distributor
terminal whose wire leads to the plug' of number
one cylinder or whichever cylinder is being timed.
The cam may then be tapped down to a tight fit
on the taper and the locking nut replaced and tight-
■ened.

To test the accuracy of this adjustment make
«ure that the electrical connections between battery,
switch, coil and breaker are complete. Disconnect
irom the coil the high tension cable that leads to
the center terminal of the distributor. Place the end
of a wood-handled screwdriver within Ys inch of
the coil terminal from which the high tension cable

BATTSnr SYSTEMS

srorr/ror a/trrcfry

■lONlTioN smrctt
Figure 8T. — Battery Ignition Using Magneto Types of DI*-
tributors. Top; Independent Syatem. EqiAjow.-. fiww.-
lilned Ignition -DvnMtio Ssb\.b\ii l,'R'iTM\-

206 AUTOMOBILE IGNITION

was removed and allow the blade of the screwdriver
to be in contact with some metal part of the engine
or ear. With the spark lever on the steering wheel
nearly retarded, crank the engine slowly until a
spark passes between the coil terminal and screw-
driver. Then note the position of the piston in its
stroke, which should be exactly at top center or
just past top center.

REMY IGNITION DYNAMO

This type of Remy equipment, which was in use
prior to the systems just described, consists of a
lighting dynamo on one end of which is mounted a
standard magneto type distributor and breaker, the
breaker cam being attached to the end of the dy-
namo armature shaft. The breaker is similar to
those found in either battery or magneto equipment,
having a two- four- or six-lobe cam operating an arm
which is pivoted at one end and which carries one
of the contacts at its other end. The cam strikes
a fibre bumper attached to the center of the arm.
The contact points are of iridium-platinum and one
of them is made adjustable by being mounted on the
end of a screw passing through a boss and held in
position by a locking nut. The opening between
the contacts when fully separated by the cam should
be from fifteen to twenty-thousandths of an inch.
With this adjustment the gap between the spark
plug points should be from twenty to twenty-five-
thousandths of an inch.

The distributor, as in the Remy systems already
described, is of the jump spark type having a rotor
segment revolving close to but not touching the pins
from which connection is made to the spark plugs.

The gap between the segment and the pins should
be six-thousandths of an inch. Near the top of the
outside face of the distributor plate is the head of
a small button called the timing button. In the rim
of the large gear which carries the distributor rotor
is a small depression into which the inner end of
ismrmf/ciXL

this button fits when the depression is directly back
of the button. '

To use this timing button, crank the engine until
the piston of number one cylinder is at top dead
center between compression and firing strokes. With
the dynamo armature shaft free to revolve, press
in on the timing button and ttiftu \M.xTi fti^ ^.-KastosK*

210 AUTOMOBILE IGNITION

^ shaft until the button is felt to drop into the depres-
*fiion in the distributor gear. With the armature
shaft in this position the dynamo shaft should be
ooupled to its driving member. It is not necessary
to pay any attention to the breaker contacts or the
position of the distributor rotor while making this
setting. The ignition device is now in position to
^ive a spark and the cable from the plug in number
one cylinder should be connected to the lower left-
hand distributor terminal with clockwise or right-
hand rotation of the armature shaft. The wiring
for this type of equipment is shown in Figure 88.

WESTINGHOUSE VERTICAL IGNITION SYSTEM

The complete ignition system of this type includes
tout three separate units;- one the batter^', another the
switch and the third being the ignition head. The
ignition head includes within its single housing the
breaker, the coil, the condenser and the distributor
so that it is almost a complete ignition system in
itself. This head may be mounted on any shaft
operated at proper speed, either on the engine direct
or on the dynamo. All of the Westinghouse units
^re of the closed circuit type and operate with a
ground return.

Breaker. — The construction of the breaker is shown
in Figure 89. This unit is carried in the lower part
of the case, below the coil, and its operation may be
observed by loosening the thumb screw and sliding
the loose section of the housing upward. The breaker
<»am has as many lobes as there are cylinders to be
£red and these lobes are so proportioned that the
'Contacts remain closed long enough to ^ allow the coil

BATTERY SYSTEMS 211

to produce a powerful spark. The breaker arm car-
ries the movable contact at its outer end and the
cam bumper between the contact and the pivot. The ,
arm extends a short distance back of the pivot point
and under this extension is a small coil spring, always
under compression, which serves to keep the contacts
normally closed and against the tension of which
the cam moves the arm. The cam is not fastened
rigidly on its shaft but is driven by means of a small
pin in the shaft and which ei;gages a hole in the

Figure 89. — Cloaed Circuit Type of Breaker (WestlnsbouBe)-

cam. This form of breaker will separate the con-
tacts and produce a spark when driven in either
direction but the pin driving connection allows a
backward travel of nearly fifty degrees before the
contacts are opened, this distance being ample to
effectually prevent an accidental backfire.

Adjustment.— The fixed contact is carried on the
end of a screw which passes through a split clamp.
This clamp is tightened or released by a locking screw.
To make the adjustment the contatAa sVisvi^i fe%\.N«.

212 AUTOMOBILE IGNITION

inspected. If they show pitted or irregular surfaces
these should be smoothed with a fine file. The clamp-
ing screw should be loosened and the adjusting screw
which carries the contact should be ^turned with a
screwdriver until with a loba of the cam against the
bumper of the moving arm, the contacts are sep-
arated eight thousandths of an inch. With the final
setting made, care should be exercised to make sure
the contact surfaces come together squarely.

Distributor. — The distributor is carried in the top-
most part of the vertical unit and is exposed by
loosening two snap springs and lifting oflf the cap
with its terminals. The distributor is of the wipe
contact type with the segments for the spark plug
cable terminals imbedded in the moulded cap. This
cap carries as many terminals as there are cylinders
to be fired, but of course, inasmuch as the coil is car-
ried in the ignition head, the central connection for
the coil as found on the usual types of distributor,
is not required. The high tension vrinding of the
coil, which is between the breaker below and the
distributor above, is connected with a metallic ring
which surrounds the vertical shaft and just under
the distributor rotor. At the outer end of the rotor
are two round carbon hrushes in a vertical tube and
one above the other. The bottom brush bears on and
travels around the metallic ring to which the coil
winding attaches while the top brush presses upward
against the track in which are located the segments
for the spark plug lines. The secondary current is
carried by the two brushes in the tube from the ring
to the .various segments as the pistons of the cylinders
come into their firing positions.

Tlie hole in the rotor which fits over the shaft has

BATTERY SYSTEMS 213

one side flattened and the shaft likewise has a flat
si^e so that replacement must be made in the correct
position. Touching the brush holder is a small flat
metal extension which is so placed that its free end
comes within about three-eighths of an inch of the
shaft. This device forms the safety spark gap, the
high tension current jumping from the metal piece
to the shaft should there be a break or undue resist-
ance in the lines to the spark plugs.

The distributor brushes should slide freely in the
holder and the spring should push the top brush out
so that it extends about one quarter inch above the
holder when the distributor cap is removed. The
brushes should be held firmly enough by their springs
so that they never fall completely out of the tube.
Always be sure that both brushes are in place. The
track inside the cap, around which the distributor
brush travels, should occasionally be wiped free of
carbon dust and other foreign matter.

Condenser. — The condenser is carried in the same
compartment with the breaker, mounted on the same
base, and on the opposite side of the shaft from the
breaker. Two short leads from the condenser con-
nect this unit with the contacts so that it is between
them as in usual practice.

Resistance. — To prevent excessive flow of primary
current at low speeds or when the switch is by acci-
dent allowed^ to remain on for a considerable time
with the engine idle, a short coil of resistance wire
is inserted in the low tension circuit. This resist-
ance, called the ** ballast resistor'' may be carried on
the switch unit or in the box with the fuses. It is
electrically connected in series with the battery, the
contacts and the low tensioii ^mfiim^ ^1 ^^ ^<s^* ^^st

214

AUTOMOBrLB IGNITION

insertion in a fuse box this resistance is made of the
same dimensions as a standard three-eighths inch
fuse and for mounting on the switch it is made rec-
tangular in shape. This unit may in some cases be
carried in a box by itself.

C ToJparHfifug$

jHiMimmt'

tnterrupter
Conl(&ts

^hiributer Sn/^Aes

'tfHfuctioo Coll

To Ignition (/nil
XorKknm inmliprnSwilch

Ignition
Switch

fu9Z Box^

Bottoiy

From Bat torf

Figure 90. — ^Wirini

: of Vertical Ignition Head with One Way
Jwitch (Westinghouse).

In case this resistance should be broken or other-
wise rendered inoperative its terminals may be tem-
porarily connected with a piece of wire, or, in the
fuse box type, wiih a standard five ampere fuse. In

BAXTKRT S7STBMS

2iet

all sach cases care most be exercised to tarn off the
ignition switch with the engine idle. iContanued
operation without this resistance in circuit would
result in serious burning of the breaker contacts and

ToSporiiPlu^S

■0'3lni(iler Snii/ia

FlEure 91. — Wiring of Vertical iBnitlon Head with Reversing
Switch (WeatlnKhouse).

the engine should not be operated without it except
in cases of emergency.

Switches. — The complete wiring plan for the equip-
ment having but one primary \jetmvMi Sa. ^^^r^n^

216 AUTOMOBILE IGNITION

Figure 90 and the connections for the reversing switch
unit are shown in Figure 91. With the ignition head
having but one primary terminal on the housing a
single pole switch is used to connect the negative
side of the battery with this terminal of •the head.
This switch may be either of the lever or snap type
and may be mounted on the same plate with the
lighting switches.

In installations having a vertical head with three
primary terminals a double pole switch of the revers-
ing type is used. This switch changes the direction
of the primary current across the breaker contacts
each time the switch is turned oflf and on again.
This reversal tends to prevent excessive deposits of
metal from accumulating on either of the contacts
but carries the material of the contacts first one way,
then the other.

Timing. — The spark control rod should be con-
nected with the lever on the ignition head and the
hand control lever on the steering wheel should be
set at about one-tenth of its full travel away from
full retard. The piston of number one cylinder should
then be raised to top center between the compression
and firing strokes.

The distributor cap may then be removed and the
driving shaft rotated in the direction it is driven by
the engine until the brush end of the distributor rotor
coincides with the V notch in the upper edge of the
outer casing. At this point the breaker contacts are
just opening, and with the several parts in this
relation the driving couplings should be secured.

If the ignition head is mounted on the dynamo

the positions just described may be obtained by rotat-

ji?^ tJie dynamo shaft with its coupling disconnected.

BATTERY SYSTEMS

21T

Should it be impossible to have the V notch regis-
tered as described, mount the ignition head in place
and make all drive shaft connections. Then turn the
complete unit around on its shaft in the direction
that the shaft rotates when driven by the engine
until the end of the rotor coincides wth the notch.

lonHionTerrainab

SwHch
Term

rminal *(f

istributor Plate

nJcrruplerCbver

Oil

1--(]|^^

3*e

InlciTupferCbdbads

Figure 92. — ^Vertical Ignition Head Containing Coil, Con*
denser, Br.eaker and Distributor (Westinghouse).

With the parts in this position, having the piston of
number one cylinder at proper top center, connect
the spark control rods with the hand advance lever
and make all drive shaft connections. Then turn the
complete unit around on its shaft in the direction,
that the shaft rotates wYien fiiTSN^TL \x^ "O^sr. ^x^^iss^fc.

218 AUTOMOBILE IGNITION

until the end of the rotor coincides with the notch.
liVith the parts in this position, having the piston of
number one cylinder at proper top center,, connect
the spark control rods, with the hand advance lever
one-tenth advanced. In Figure 92 is shown the ex-
ternal appearance of the vertical ignition head.

WESTINGHOUSE IGNITION DYNAMOS

These units include a breaker and automatic ad-
Tance mechanism mounted on the dynamo armature
fihaft at the end opposite the drive and a distributor
-carried above the breaker. The coil is in some cases
a separate unit and in others is mounted within the
•dynamo case. These equipments are of the- open
•circuit type, the breaker contacts being normally open
^nd the spark being produced by the spring actuated
opening which occurs after they have been closed by
the breaker cam. In common with practically all
other Westinghouse equipment the units are all of
the one wire or ground return type.

Breaker — The earlier installations make use of an
ignition-dynamo carrying a breaker (shown in Figure
22) which has two sets of contacts connected in series
with each other and in circuit between the two termi-
nals which appear on the lower side of the breaker
•case. One of these terminals is grounded while the
other is connected through the coil and switch to the
battery. , The wiring for this type is shown in Figure
:93 at the top.

The two breaker contacts are supported by a flexible

arm pivoted in one end of the case. Between the

two contacts is a crosswise pin underneath which

passes the hooked end of another arm which is hinged

BATTERY SYSTEMS

Figure 93. — Wiring o[ Combined Ignition Dynamos In "V

inghouBO Systems, Top: Double Contact Break"

with Separate Coil. Center: Separate Coll

With Reversing Switch. Bottom ;

Coll and CondenBer In Dynamo,

with Separate Switch.

220 AUTOMOBILE IGNITION

in the opposite side of the housing. Attached to this
second arm is a flat spring which passes above ^the
hook and holds the pin down in place. The breaker
spring tends to hold the contacts apart Until the arm
having the hooked end is struck by the cams at which
time the contact points are allowed to come together.

The lower contacts of each pair are adjustable,
being carried by the upper ends of screws which-
thread into two blocks. The screws are held from
turning by other clamping screws passing into the
blocks so that with the correct setting of the gap
once made it may be maintained.

A later type of breaker used with ignition-dynamos
is also of the open circuit type in which the contacts
are held apart by a spring until pressed together
by the cams, but this type has but a single pair of
contacts as shown in Figure 60. The movable con-
tact is carried near the end of a flat piece of metal
which pivots at one side of the housing. Above this
metal piece is a second arm also pivoted at the same
side. The end of this upper arm, which is near the
contacts, has lips which curve around the piece carry-
ing the movable contact and which serve to lift this
movable member away from the fixed contact because
of the action of a coiled spring which presses against
the end of the upper arm on the side of the pivot
which is away from the contacts.

This type of breaker also has two terminals, one
connected with the fixed, and the other with the
movable contact. With a separately mounted coil
and switch both of these breaker terminals are con-
nected with the terminals on the coil unit while with
a coil carried in the ignition-dynamo case both breaker
terminals are connected with terminals on the switch.

BATTERY SYSTEMS 221

Wiring for this system is shown in Figure 93 in the
center.

The contacts of this breaker are closed when one
of the cams strikes a fibre bumper carried on top of
the arm which is acted upon by the coiled spring.
The bumper is prevented from being pressed too close
to the cams by a stop against which the free end of
the bumper arm strikes when released by the cams.

Advance. — In the majority of installations includ-
ing ignition-dynamos the spark advance is automatic,
being illustrated by Figure 60. The mechanism com-
prises two weights which swing on pivots and which,
with the centrifugal force developed by their rapid
rotation, act against the tension of two flat springs.
The outer edges of these weights act as cams to close
the breaker contacts twice during each revolution of
the dynamo shaft or once for each of the cams. The
contour of the outer edges is such that with higher
sp.eeds the contacts in the breaker are held together
for a greater part of the revolution of the shaft as a
greater length of the cam weight rides past the fibre
bumper. This peculiarity of action advances the time
of the make and break of the contacts with the engine
speed and also performs the further function of keep- ,
ing the actual time during which the contacts are
together nearly constant, regardless of the speed of
the engine, for the reason that they are held closed
during a greater part of the revolution at high speeds ;
when, in the usual constructions the time of contact
would ordinarily grow less. In some installations these
centrifugal weights are omitted and an ordinary cam
gubstituted when automatic advance is not wanted.

Adjustment, — In adjusting the breaker of the igni-
tion-dynamo the setting of the stcr^ ^.^'ajvxv^V ^>x>i55^

222 AUTOMOBILE IGNITION

the spring arm strikes should first be checked. With
the engine slowly cranked until one of the cam weights
depresses the bumper and closes the contacts there
should be a gap of 3/64 of an inch between the spring
arm and the stop. This gap may be altered by loosen-
ing the screws which hold the stop to the breaker
case and changing its position.

After the stop is adjusted the opening between the
breaker contacts should be made from five to eight
thousandths of an inch while the spring arm of the
breaker is against the stop. The contact opening
may be changed by loosening the clamping screw
in the block which carries the fixed contact and then
turning the contact screw one way or the other until
the proper setting is secured. The clamping screw
should then be tightened. After making this adjust-
ment be sure that the contacts open positively and
that the arm moves clear up against the stop when
released by the cam weight with some tension of the
coiled spring still remaining to hold it in this position.

The cam weights should turn freely on their Sup-
porting pins and should clear the back of the weight
support by approximately one hundredth of an inch.
These weights should show no lost motion between
their interlocking surfaces. In making any adjust-
ments make sure that when the engine is slowly
cranked both cam weights depress the bumper arm
sufficiently to positively close the contacts, otherwise
there will be a tendency to miss fire on every second
cylinder at low speeds and if the contacts are more
or less worn.

When the cam weights are in their inner position

their springs should just touch the fibre covered pins

on the weights without exerting any appreciable

BATTERY SYSTEMS 225

pressure. -Should it ever become necessary to adjust
these springs, bend their supporting arms and never
the springs themselves.

Distributor. — This part of the ignition-dynamos i»
very similar to the distributors used on magnetos.
The rotor is attached to a gear which is driven from
the dynamo armature shaft at one-half its speed and
carries a carbqn brush backed by a small coiled spring.
This brush travels around a track in which are located
segments equal in number to the number of cylinders
on the engine to be fired. In the center of th^ distri-
butor cap is a round carbon .brush which connects
with the terminal for the high tension lead from the
coil and which carries the secondary current to the
center of the rotor where it enters a small metal disc.
This disc is in metallic connection with the rotor
brush.

The distributor brushes should slide freely in their
holders and their springs should push the brushes
out so that they extend from the holder about one-
fourth inch when the distributor cap is removed.
The brushes should, however, be retained firmly by
their springs so that they never tend to fall com-
pletely out of the holders.

Coil. — In the later types of ignition-dynamos the
coil is imbedded in the insulating material of the
distributor plate and all necessary connections are
made by putting on the distributor and inserting its
holding screws. With this integral coil the condenser
is also mounted within the ignition-dynamo and, a»
is always the practice, connected between the breaker
contacts.

A separate coil designed for dash mounting is also*
used in some cases and this type of \3iw\\ <i«rcv^^ *n^^

224

ADTOUOBILHl IGNITION

switch on one end and the several terminals at the
other end. "With the separate coils a safety spark
gap is mounted on the terminal end of the housing,
this gap allowing the high tension current, in ease
of a break in the secondary connections, to escape
through the line for the positive side of the battery
to the ground of the car. The condenser is then
carried in the coil housing tather than in the ignitiim-
dynaino as with those units having integral coils.

Isnlt Ian-Dynamo (WestlnghoUBe).

This wiring is shown in Figure 93 at the bottom.

Switch. — ^With some ignition-dynamo equipments a
kick lever switch is used which iias but the two posi-
tions "OFF" and "ON."- This switch may be car-
ried on the coil housing or mounted as a separate
unit. In connection with the lever in this type of
«witeh there is incorporated a reversing plug which.

BATTERY SYSTEMS 225

depending on the position in which inserted, sends
the current through the breaker contacts and primary
circuit in either one direction or the other. This plug
has metallic pieces on 'opposite sides which engage
four contacts inside the switch in alternate pairs as
the plug is turned from one position to another in
inserting. It is desirable in practice that the plug
be inserted as often in one position as in the other
to distribute the deposit of metal equally between
the breaker contacts. . With some outfits a snap type
of rotary reversing switch is used which reverses the
current direction each time it is turned off and then
on again. The handle of this rotary switch is always
turned in a clockwise direction, first completing the
ignition circuit, then breaking it.

Timing,~'With. the piston of number one cylinder
at top center between the compression and firing
strokes the armature shaft of the ignition-dynamo
should be turned in the direction it is driven by the
engine until the breaker contacts are just opening.
The breaker housing should be in its retarded posi-
tion while making this setting.

The distributor gear is meshed with the small pinion
on the driving shaft so that the mark at the edge
of the gear lines up with the tooth of the pinion that
is slightly beveled. With the piston of number one
cylinder at top center as described, the setting may
be made by removing the distributor cap and turning
the driving shaft backward until the line of the dis-
tributor rotor block corresponds with the line on the
end bracket. The engine and driving shafts should
be coupled with the parts in these relative positions.

The external appearance of a typical Westinghouse
ignition-dynamo is shown in Fi^T^^^*

226 AUTOMOBILE IGNITION

CONNECTICUT

Connecticut ignition systems are of the closed cir-
cuit type, the breaker contacts being normally held
together by a flat spring until forced apart by the
action of the cam. While the engine is running the
contacts remain closed for a sufficient length of time
to allow very complete saturation of the coil magnet
and consequently a powerful spark which is increased
in strength as the engine speed decreases because of
the greater length of contact time measured in frac-
tions of seconds.

The primary circuit in Connecticut systems is not
grounded at any point in the mechanism, the breaker
contacts with their mountings as well as the primary
winding of the coil being insulated from any con-
nection with metal which leads to a ground on the
car and the primary winding of the coil being com-
pletely separated electrically from the high tension
or secondary winding.

Breaker, — The new style breaker. Figure 95, com-
prises two contact points, one mounted in a fixed
position on the end of a screw which passes through
a stationary block while the other is carried by one
end of the breaker arm. The breaker arm is pivoted
at the end farthest from the contact and near its
center this arm carries a revolving fibre roller or else
a fibre block attached to the arm. Attached to the
pivoted end of the arm is a fiat spring which is bent
back under a bracket with sufficient tension to hold
the contacts closed until the fibre bumper or roller
is acted on.

The breaker cam has as many lobes as there are
cylinders to be fired and fits over the upper end of

BATTERY SYSTEMS 227

its shaft ■with a taper, being pressed on to the shaft"

and held from turning by a locking nut.

The construction of the breaker is such that there
are no moving wires required. The breaker proper,
that is, the arm and the two contacts, are mounted
on a separate base which turns bodily inside of the
housing when the time of the spark is advanced or

Fliure 35, — Breaker with Stationary Outside Terminals

retarded. The terminals for the outside wires lead*
ing to the coil and switch are carried by the stationary
housing and inside the housing these terminals end
in thin flat springs which are shaped so that their
free ends bear against segments carried by the base
on which the contacts and arm are mounted. Oiift
of these segments carries tha axm. -sA^fe "fiasi «:Soks.

228

AUTOMOBILE IGNITION

carries the fixed contact point. As the inner base
plate is moved for advance or retard the spring ends
of the terminals slide on the segments so that electrical
connection is always maintained regardless of the
position of the moving base.
Adjustment. — The fixed breaker contact may be

Figure 96. — Construction of Closed Circuit Breaker with
Jump Spark Distributor (Connecticut).

moved to alter the distance between the points wh^i
they are open. This contact is carried by a screw
passing through a bracket and locked in position by
a nut on the screw which turns up tight against the
bracket The contact end of the screw is provided

BATTERY SYSTEMS 229

with, a hexagon head which m3.y be turned with a
wrench after the locking nut has been loosened.
With a lobe of the cam holding the cfontacts at their
greatest distance apart the gap should be set to one
fiftieth of an inch.

Distributor, — The wiping brush contact used in the
distributor of former Connecticut equipment has been
replaced with a jump spark type of mechanism in
which the rotor just clears a number of pins which
connect with the leads to the several spark plugs.
The construction is shown in Figure 96. The rotor
fits over the top of the shaft and is driven by means
of a key and keyway. It carries a brass strip whose
outer end carries current to the spark plug lines
and whose inner end forms a flat spring contact which
presses up against a central pin passing through the
center of the distributor cap and which connects with
the line from the high tension winding of the coil.
The distributor cap is provided with small holes for
ventilation but these are so placed that the unit is
still dust and moistuFC pjr oof.

Coil. — The coil is carried in a cylindrical housing
which also contains the condenser and on the outside
of which is carried a safety spark gap having one
electrode connected with the high tension winding
of the coil and the other end attached to the ground
connection from the other end of the secondary. The
terminals for the primary circuit are brought out at
one end of the housing and those for the secondary
at the side. These circuits are shown in Figure 37.

Advance. — ^A large number of Connecticut systems
are fitted with an automatic spark advance mechanism
which is regulated to accommodate the cliar^<il<K«\^^^
of the engine to which attacii^flL. \xl ^^JaKt ^-siRfc^-.

230 AUTOMOBILE IGNITION

including many small engines, this automatic advance
is omitted and manual operation alone depended on.

The advance lever is designed to move the breaker
base plate inside of its housing and is pivoted on the
stationary housing itself. The inner end of the lever
engages a pin fastened to the breaker base and when
the outer or control end of the lever is moved in one
direction the lever fulcrums on this pin and moves
the inner end and the breaker base in the direction
opposite to that in which the lever itself travels.
To secure a retarded position of this mechanism the
lever is moved contrary to usual practice in a direc-
tion opposite to that in which the shaft rotates and
to advance the spark the lever is moved in the same
direction as the shaft travels.

Timing. — To set the breaker, its driving shaft is
first permanently connected to the engine shaft with-
out regard to the relative position of the parts of the
breaker and engine. With the gears meshed or the
couplings fitted the distributor cap is removed and
the distributor rotor lifted from the end of its shaft.
The nut on top of the cam is then removed and the
cam loosened by prying up while gently tapping it.

The piston of number one cylinder is now to be
brought to top dead center between compression and
firing strokes and the advance lever on the breaker
is to be set in the fully retarded position. The cam
should then be placed in position on its shaft so that^
with the distributor rotor in place the outer end of
the rotor will be opposite the pin in the cap which
fastens to the terminal leading to the spark plug in
number one cylinder. The cam is then carefully
moved into position so that with rotation in the direc-
fjon it Is driven from the engine one of the lobes is

BATTERY

just about to press against the fibre roller or bumper
and cause the contacts to separate. With the cam
in this position it should be tapped onto the end of
the shaft, and the locking nut should be replaced and
tightened. Before placing the cam on its shaft it is

always best to lightly oil or grease the surfaces which
6.t together so that future removal may not be hin-
dered by the formation of nist.

Switch. — Many Connecticut installatic'Ds, SxiR^is^$«. w
unique type of switch that, is desv^o-feftL X-i^ B»-\.'OTBSk'<N.-

232 AUTOMOBILE IGNITION

cally open the primary circuit should the switch re-
main closed for any length of time with the engine
idle. Such a condition would allow a flow of cur-
rent great enough to seriously damage the breaker
contacts and the coil if allowed to continue and
would likewise discharge the battery in a compara-
tively short time.

The switches incorporating this feature are oper-
ated by means of push buttonis which close the circuit-
when pressed in. The button is held in its closed
position by a slotted plate or by a latch entering a
notch in the body of the button, depending on the
installation. In either case the lock must be re-
leased, either by pressure on another button or by
automatic operation, before the first button can be
released to open the primary circuit.

The electrical connections are shown in Figure 97.
The releasing device consists of a small spring ther-
mostat which is heated by passage of the primary
current around it, the coil of this thermostat being in
series with the primary circuit ; also an electro-magnet
through which the current may be sent by movement
of the thermostat. The electro-magnet with its con-
tacts which are closed by bending of the thermostat
forms an electric buzzer when current flows through
its coils and the hammer of this buzzer strikes the
releasing device which frees the ignition switch but-
ton, allowing it to fly out and open the circuit.

The thermostat blade in bending acts against the
spring of the arm and this spring tension may be
changed by an adjustment. With but slight tension
the switch will be opened about thirty seconds after
the current starts to flow, while with full tension of
the adjustment a period- of about four minutes will

BATTERY SYSTEMS

para before this action takes place. The time is set
so that plenty of opportunity is given to complete
the crankiiLg operation after the ignition switch is
closed.

^ OROUNO

\ /T ^

1 '

~(0™-

Ifl

5 .

WTTERYOF

■i

(

FlKure 98.— Wiring of Connecticut Systema. Uovet 1*.1V.

Ford Installation. Upper Rlghf. "GOM." IS'tvWeT ^xift."^"

Switch. Bottom : "GO" Igniter aiv4 '■«-" ^•«'i'i-<i^-

234

AUTOMOBILE IGNITION

With the switch button closed battery current
enters the switch and flows around the heater tape
which is wound around the blade. The amount of
current which flows when the breaker contacts are

Figure 99. — ^Wipe Contact Distributor and Closed Circuit

Breaker (Connecticut).

not in action, as with the engine idle, is far in excess
of that passing with the breaker operating. This
excessive flow causes the thermostat blade to bend
and to make a contact which sends the current through

BATTERY SYSTEMS 235

the magnets. The vibrator action thus set up imme-
diately opens the primary switch contact.

Wiring. — The complete wiring connections, both
internal and external are shown in Figure 37 for the
equipment described but without the automatic kick
oS switch. The switch shown in this diagram is of
the rotary reversing type oftentimes used. It will
be noted that the primary circuit through the breaker
and coil is completely insulated as already mentioned.
It is desirable that the primary wires between coil
and breaker be as short as possible, twelve inches
being the maximum practicable length. The coil
terminals are of such shape that with the proper
connections once installed it is impossible to make
a wrong replacement. Diagrams of the connections
for other and older Connecticut systems are shown
in Figure 98, and some of the constructional features
in Figure 99.

BOSCH

The Bosch battery ignition system is primarily
designed for operation in connection with any one of
the magnetos made by this company. It is of the
closed circuit type with the breaker contacts normally
together and held in this way except during the time
when opened by the cam. Ignition may be had either
by battery alone with one set of plugs, by magneto
alone with a second set of plugs or by battery and
magneto operating together in synchronism and with
both sets of plugs sparking. The coil housing con-
tains a vibrator which may be used to give a stream
of sparks, or this vibrator may be cut out, when
the.battery system will deliver a single spark for ea^K
firing stroke.

236 AUTOMOBILE IGNITION

The battery system consists of a combined coil and
switch and a separate breaker and distributor all
completely independent of the. magneto. The two
systems, battery and magneto, are brought together
only at the switch and either system could be used
with the other completely removed.

Breaker. — The breaker and distributor are shown
in Figure 100. They are supported by a tube formed
with a sleeve in the lower part, this sleeve fitting over
a shaft driven by the engine at one-half crank shaft
speed and secured to the tube and sleeve by a taper
bolt. The breaker cam is approximately square with
rounded comers and is secured to the shaft by a key.

The breaker arm is straight, is pivoted at one end,
carries the movable contact at the other end and a
fibre bumper near its center, the cam striking against
this block to open the contacts. The fixed contact is
carried by a block which is insulated from the breaker
base while the arm and movable contact are in metal-
lic connection with the base and therefore grounded.
The housing of the breaker is provided with a ter-
minal from which a wire leads to the metal of the
car for a ground connection of low resistance, the
metallic supporting parts of the unit being carried
by ball bearings which do not provide a proper con-
nection in themselves. The other terminal on the
breaker housing connects with the fixed contact point
through its supporting block.

Adjustment.^ — The breaker mechanism may be ex-
posed by displacing the side springs and removing
the distributor cap. The distributor rotor may be
lifted off its driving pins and the distributor housing
also removed. The fixed contact point is carried on
the end of a screw provided with a hexagon head

BATTERY

fnlt. Bottom ; WirlnK. t.'BQat^i.'i

238 AUTOMOBILE IGNITION

which may be turned with a wrench. This screw
threads into the supporting block and is prevented
from turning by two locking nuts on top of the block.
With the cam in position to fully separate the con-
tacts the gap between them should be set at fifteen
thousandths of an inch.

Distributor, — TJiis part of the unit is of the wipe
contact type, a carbon brush backed by a small coil
spring being inserted in the rotor so that it travels
around the inside of a cylindrical track in the dis-
tributor cap. In this track are placed segments,
one for each cylinder to be fired, which are con-
nected withr the spark plug cable terminals on the
outside of the cap. The central terminal of the
distributor cap carries the end of the lead from the
secondary winding of the coil. Inside the cap this
terminal connects with a second small carbon brush
whose spring presses it down onto a tube carrying
the rotor brush which conducts the high tension cur-
rent to the segments. A brass plate is attached to
the top of the breaker cam shaft with a taper head
screw and this plate carries two pins which fit into
openings in the rotor and provide driving connection.
The distributor cap is supported on the upper edge
of a brass ring which surrounds the breaker mechan-
ism. Moving the side springs allows the removal of
the cap and also allows the ring to be lifted off, com-
pletely exposing the breaker and the distributor rotor.

Coil. — The coil is carried in a cylindrical housing
at one end of which are the several primary and sec-
ondary terminals and at the other end of which are
the switch, the vibrator and the condenser. The con-
struction is shown in the center of Figure 100.--
A movable brass cover carries the switch lever and

BATTERY SYSTEMS 239

is attached to the coil housing by a bayonet joint.
In the center of this cover is a press button used for
starting the engine on the spark and also as an
auxiliary switch, the turning of which brings the
vibrator into action or cuts it out of the circuit.
A pin set into the end of the coil body engages an
opening in this brass cover and causes the coil body
and the cover to move together. The switch contacts
are carried by the other end of the coil and movement
of the cover permits operation of these switch con-
tacts. The movable contacts carried by the coil body
register in the diflPerent positions of the switch lever
with the proper contacts which attach to the ter-
minals fastened to the end of the coil housing oppo-
site the switch lever and cover. Four positions are
provided for the lever; **0'' is the off position, **B''
provides battery ignition only, **MB'' gives both
battery and magneto ignition at the same time and
**M'' allows magneto ignition only. Partial rotation
of the coil by the lever causes the different switch
contacts to engage and secure these results.
With the switch lever turned to either the **B''
,' or **MB'' positions, a pressure on the central button
will complete the primary circuit around the breaker
contacts regardless of the position of these contacts,
open or closed. Further pressure of the button opens
the primary circuit through the coil with the result
that a spark is produced at the plug of the cylinder
ready to fire so that ignition will take place provided
there is a charge of inflammable mixture in this
cylinder at the time.

The vibrator may be brought into action by press-
ing in on this button and rotating it slightly to the
left or until the pointer is \q^^t$^ *0^^ ^^^^

240 AUTOMOBILE IGNITION

** START.'' The button will remain in this position
and a stream of sparks ,will be produced instead of
a single contact spark as in ordinary running.

Timing, — In order to make use of the *'MB'' posi-
tion of the switch, in which both battery and mag-
neto are furnishing sparks to their separate sets of
plugs, it is necessary that both systems operate at
exactly the same instant, otherwise the spark that
passes first will ignite the mixture and the second
one will be wasted. In case the sparks were not
synchronous and one or more cylinders should be
fired by the battery system while the remainder were
fired by the magneto, the difference in timing would
produce a very unpleasant unevenness in the run-
ning of the engine.

To make the original setting the sleeve shaft of the
breaker should be placed loosely over the driving
shaft intended to receive it. The advance lever should
be connected with its operating rods in the usual way.
The advance lever of the magneto should be fully
advanced as should also the advance lever for the
battery breaker and the engine should be cranked
until the magneto breaker contacts are just about to
separate. The sleeve shaft should then be turned in
the direction it will be driven until the battery breaker
contacts are about to separate. Marks should then be
made on the sleeve shaft and on the driving shaft so
that the breaker may be removed and replaced in
exactly the same position, the accuracy of this replace-,
ment being quite essential.

The taper bolt used for driving requires that a flat

be filed on the driving shaft and after this work has

been performed the sleeve shaft may be returned to

position and secured by the bolt. The magneto

BATTERY STSTDMS 241

breaker and battery breaker should now open their
contacts aimultaneously. The wiring oi this system is
shown at the bottom of Figure 100.

NORTH EAST IGNITION

The battery ignition equipment made -by the North
East Electric Company is of the open circuit type
and the construction is shown in Figure 101. The

complete unit consists essentially of three assemblies ;
the ignition coil, the breaker and distributor, and the
base assembly, which includes an automatic advance
mechanism.

Breaker. — The breaker arm is mounted on a pivot,
from which it is insulated by means of a fibre buefeMi^,
and is provided with a fibre biocfe Tve«.i \\» <Lft'c&.et,'Oas>

242 AUTOMOBILE IGNITION

breaker cam lobes striking against this block while in
action. The contacts are normally held closed by a
coiled spring, one end of which is attached to a post
in the housing, while the other end fastens to a lug on
the breaker arm.

The statioiijary contact is carried on the end of a
ficrew which threads into an arched support and is
locked in position by a nut on the contact end of the
screw. "With the contact points fully separated, their
■distance apart should be twenty thousandths of an
inch. With this setting of the breaker, the spark
plug gap should be made thirty thousandths of an
inch.

The breaker arm may be removed by disconnecting
the pig-tail from the housing binding post and lifting
the arm from its pivot. The spring attached to the
lug on the arm will slip off as soon as the arm is
raised sufficiently from its normal position. The sta-
tionary contact screw can then be taken out of its
support.

The breaker cam should be lubricated once or twice
in a season by the application of a very small quantity
of vaseline to its working surface. Excess lubricant
should be removed as it would tend to an accumula-
tion of oil on the contacts.

Distributor. — The distributor is of the wipe contact
type with a brush carried in the outer end of the rotor
and following the segment tract, while the ^central
contact is made by a flat spring bearing against a
terminal stud in the center of the distributor cover.

The track followed by the brush in the distributor

•cover should be wiped dry and clean about once in

^j^rh two thousand miles of running. After each

<^leaning, the track should be lubricated by applying a

BATTERY SYSTEMS

244 AUTOMOBILE-IGNITION

small amount of vaseline, all excess lubricant being
carefully wiped from the cover before replacement.

Condenser. — This unit is carried in a sealed case
located in the breaker housing close to the contacts.
The entire condenser may be removed by disconnect-
ing its two leads from the breaker housing binding
posts and then unscrewing two holding nuts which are
on the under side of the housing.

Coil. — The ignition coil is contained in a separate
housing which forms a part of the ignition unit. The
coil housing is attached to the base unit by means of
four screws, and this housing serves also as a cover
for the automatic advance mechanism. The high ten-
sion terminal on the coil provides a safety spark gap
between the terminal stud and the surrounding metal.

Automatic Advance, — The spark advance is cared
for by a combination of manual and automatic con-
trol. The automatic device is of the centrifugal type
and consists of a set of weights carried on pivots
which are driven directly from the engine shaft.
These weights are normally held in place by small
coiled springs, against whose tension they act and
rotate the vertical breaker shaft for a part of a turn
relative to the engine driving shaft.

Under ordinary conditions the original Supply of
grease in the advance housing will be sufficient for
two or three seasons running. New grease should be
applied with moderation to avoid overflowing the
compartment, although a vent is provided in the front
of the base casting through which any excess lubri-
cant may escape.

Wiring. — The wiring and internal connections are

shown in Figure 102. One side of the battery is

grounded, but between switch, co\\ and \iT^ak^T t\v^

BATTERY SYSTEMS 245

connections are of the two wire type for the reason
that the ignition part of the combination switch is of
the reversing type.

Timing. — ^With the piston of number one cylinder
brought to upper dead center between the compression
and firing strokes, the breaker should be placed in its
fully retarded position. This is done by disconnect-
ing the hand advance and turning the breaker hous-
ing as far as it will go in the direction that the verti-
cal shaft rotates.

The distributor head and rotor should then be lifted
off and the cam nut turned backward with a broad
bladed screwdriver until the cam is free to turn op.
the shaft. The rotor should then be replaced tem-
porarily and the cam slowly turned until the rotor is
in position to make normal contact with the distrib-
utor segment for number one spark plug.

Adjustment may then be made by turning the cam
forward just enough to separate the contacts, then
turning it slowly back until the contacts just come
together, at which point the cam should be allowed to
remain.

With the above setting, the distributor rotor should
be again removed and the cam locked securely in
position by tightening the jslotted nut that holds it.
With the rotor then replaced, the vertical shaft should
be rocked backward and forward as far as the slack
in the gears will permit. When the shaft is rocked
forward, the contacts should be held apart; while,
with the shaft rocked backward, the contacts should
be closed.

CHAPTER VIII

FORD IGNITION

The ignition system used on the Ford car is entirdy
unlike any other equipment at, present in use and
requires individual and specialized treatment in all
of its parts. This system includes a magneto which
is in reality a small alternating current dynamo built
into the engine flywheel. In connection with the
magneto there is used a set of coils equipped with
vibrators giving a stream of sparks, there being one
coil for each cylinder of the engine. The ignition sys-
tem is completed by a commutator which sends the
magneto current to the proper coil at the proper time,
and also the usual spark plugs and wiring between the
various parts of the system.

THE MAGNETO

The Ford magneto consists of a set of sixteen V
shaped permanent magnets which are mounted on the
engine flywheel and which revolve with it, also a set
of sixteen small coils wound on iron cores and held
stationary on the engine crankcase in such a position
that the set of sixteen magnets revolves with the outer
ends very close to these coils. The appearance of
these two parts is shown at the bottom of Figure 109.

The sixteen permanent magnets are so placed that
the adjacent ends of any two magnets are always of
the same magnetic polarity. Each magnet is mounted

246

FORD IGNITION 247

in such a way that its positive pole is next to the posi-
tive pole of the magnet at one side and so that its:
negative pole is next to the negative of the magnet on
the other side. The whole arrangement, as shown in
Figure 103, then becomes in effect a compound magnet
having sixteen outward pointing poles, eight of them
positive and eight negative. The magnetic lines of
force passing out of any pair of adjoining positive
poles travel to the negative pol«s which are found on
either side of the positives. From eight of the poles,
(the positives) the magnetic lines of force are then
traveling outward, and to eight more of the poles:
(negatives) the lines are traveling inward.

It was explained in Chapter Two that a current of
electricity will be induced in a coil of wire wound on
an iron core if the magnetism of the core changes in
intensity or reverses its direction entirely. If then
a coil carried on an iron core were moved around the
circle formed by the ends of the magnets and with
the end of the coil's core always pointing toward the
magnet poles, a flow of current would take place
through the coil each time the flow of magnetism
through the core changed its direction. In the Qjase
of the Ford magneto there would be sixteen separate
impulses of current because the direction of the mag-
netic lines of force would change in its flow each
time the coil moved from a magnet end of one polarity
to an end of the opposite polarity. As the coil passed
from in front of a positive pole to a negative pole, the
flow of current would be in one direction through the
coil winding, and as it passed from in front of the
negative pole toward another positive the flow of
current through the coil winding would take place
in the opposite direction. TTiie c;vxTTeiv\> Nqcs>6\^ '^'st^b-

248 AUTOMOBILE IGNITION

fore be of the alternating type because of this change
in the direction of flow.

In the construction of the Ford magneto there are
sixteen of these coils spaced, the same distance from
«ach other as are the ends of the magnets. One con-
tinuous winding passes around all of the sixteen coils
as shown in Figure 103, and this winding reverses
its direction of turning around the core in each alter-
nate coil. As this set of sixteen coils is stationary,
the same eflPect is secured by moving the magnets in
front of the coils, as would be secured by moving the
<;oils in the explanation already given. During* one
sixteenth of a full revolution of the flywheel with its
set of permanent magnets, the end of any one magnet
will pass from one coil to the next and a flow of cur-
rent will be induced in the coil windings. It has
already been stated that the direction of induced cur-
rent flow reverses its direction in the coil windings
with change of the magnetic polarity, but inasmuch
as the winding itself is also reversed on alternate coils,
the direction of flow through the whole length of the
winding will be in one direction during this sixteenth
of a turn. Then on the ne^t sixteenth of a turn, as
the magnets each pass to another coil in their circuit,
the current through the whole length of winding will
reverse its direction. One end of the coil winding is
grounded and the other end is led to a terminal on
top of the flj'ivheel case from which the magneto cur-
rent passes to the remaining parts of the ignition
system.

The magnets are fastened to the flywheel at their

inner ends by means of bolts through the bottom of

the V and at their outer ends are fastened by iron

plates, each plate holding two adjacent magnet ends

FORD IGNITION

Figure lOS. — Principle of the Ford Magneto. Top ; Perma^

nent Magnet Rotating Field. BolXotn-. "W\ti.«v.tv^

of Stationary A.cmfi,tuTe CoV\a.

250 AUTOMOBILE IGNITION

of like polarity. This metal clamping plate serves to
make the two poles which are held by it into a single
pole of either polarity and from this single pole the
magnetic lines of force issue if it is positive, or return
if it is negative.

The winding of the magneto coils consists of a cop-
per ribbon covered with a fabric insulating covering
which is treated to make it moisture and oil proof.
This winding is attached to the ring carrying the coils
at one of its ends so that a ground connection is estab-
lished for one terminal and the other end of the wind-
ing obtains electrical connection with the flywheel
■case terminal by means of a small brush backed by a
•coiled spring, the combination being carried in an
insulating holder fastened to the flywheel housing by
means of a flange and screws. The inner end of this
l)rush bears against the connection from the winding
ribbon.

The current from the Ford magneto changes its
■direction of flow sixteen times during each complete
revolution of the flywheel, that is, it makes eight com-
plete cycles or changes from positive to negative and
l)ack again to positive. The number of cycles at
which the current is being delivered at any given time
will therefore be eight times the number of revolu-
tions per minute that the engine crank shaft and fly-
wheel are making. The voltage from the magneto
varies from zero with the engine idle to something
over thirty at forty miles an hour. At a car speed of
S% miles an hour the voltage rises to six which is
about the lowest pressure at which satisfactory igni-
tion action is obtained. At ten miles an hour the volt-
age is approximately twelve, at twenty miles an hour
y/ js slightly over twenty and at thirty miles an hour

FORD IGNITION 251

the voltage is about twenty-eight. These figures are
for the new type of magneto which is designed to
operate the head lights as well as the ignition.

VIBRATOR AND COIL

The coil used on the Ford car is of the multiple
unit vibrating type having one complete induction -
coil unit for each of the four cylinders and having a
magnetically operated breaker of the vibrating type
on each, coil. This equipment was at one time almost
universally used in connection with dry cells, a stor-
age battery or a low voltage dynamo for automobile
ignition but today it is found on the Ford car alone.

A diagram of the coil and its circuits is shown in
Figure 104. By following the primary and secondary
current paths the action of this unit and of the
vibrator may be easily understood. With the switch
closed in the position shown by the dotted lines,
primary current will flow from the magneto terminal
on top of the flywheel case through the wire 1 to the
switch and wire 2 to the one terminal of the primary
winding. Entering the coil box by this terminal the
primary current will flow around the primary wind-
ing of the coil and will strongly magnetize the core
of the coil which is made up of a number of iron wires
formed into a oj^lindrical bundle inside the winding.
Leaving the coil, the current flows through wire 3 to
a spring blade B which is carried with one of its ends
above, but not touching, the core of the coil. This
spring blade is made from steel and is accordingly
attracted by the magnetism induced in the iron core
by the passage of the primary current.

Just above the spring blade is a stationary hx!i&s^%
bar called the bridge and tTie eoTi\.s^c\. ^csv^Xs* ^ «x^

252 AUTOMOBILE IGNITION

carried by these parts, one contact by the spring blade
and the other by the stationary bridge. The primary
current flowing through the blade passes across the
conta,cts, which are normally closed, and enters the
bridge. From the bridge the current flows by way
of wire 4 to the commutator which is a device con-
sisting of a revolving roller inside of a housing, the
roller being driven from the engine and making suc-
cessive contacts with a series of segments set into the
inside of the housing. The wire 4 connects with a
segment, only one of which is shown for purposes of
explanation. The revolving roller of the commutator
is one of the metal parts of the engine and the current
therefore flows through the segment and the roller to
the ground or metalwork. As has already been
explained, one end of the coil winding of the magneto
is connected with the ground and the primary current
returns by this metallic path- to the magneto coils,
thereby completing the ignition circuit starting with
the magneto and returning to it. Each time the com-
mutator roller rides over and makes contact with one
of the segments a circuit will be established through
the coil whose winding is connected with this segment.
As soon as the commutator allows current to flow
through the coil and around the primary winding by
way of the wires and the vibrator contacts, the core of
the coil becomes magnetic and attracts the spring
blade B. The end of the blade that carries the contact
point is then pulled down toward the upper end of
the core and the contacts are caused to separate inas-
much as the bridge A remains stationary. With the
contacts separated the primary current path is opened
and the current no longer flows. With no current
lowing the core of the coil is no longer magnetic and

FORD IGNITION

the blade B is released, again closing the contacts by
returning to its former position and allowing a furtber

Figure 104. — Circuits o( Ford Isnltlon System.

flow of current. This further flow again magnetizea
the core and the action eontinuca "«\&. "Otia *as!!^»ri»

254 AUTOMOBILE IGNITIOI^

opening and closing with exceeding rapidity, in fact
the action of the blade is to vibrate. Each opening
of the contacts stops the flow of current through the
coil and allows the core to become demagnetized, while
each time the contacts close the core is again magnet-
ized. This change in magnetic strength of the core
induces the current of high voltage in the secondary-
winding which is also wound around the iron center
and this high tension current is led through the wire
5 to the spark plug. A high tension current is induced
in the secondary winding each time the contacts sepa-
rate and the result is a shower or stream of sparks
between the points of the plug.

The secondary circuit starts in the winding of the.
coil, passes through wire 5 to the central electrode of
the spark plug and by forming the arc between the
spark plug points reaches the metal shell of the plug
which is a ground connection in contact with the metal
of the engine. Passing through the metal work, the
secondary current reaches the revolving roller of the
commutator, through the roller it passes to the seg-
ment with which the roller is then in contact and by
way of the wire 4 to the coil box. Entering the coil
box the secondary current follows wires 6 and 7 back
to the other end of the secondary winding from which
it originally issued to the spark plug wire. It will
thus be seen that the high tension current follows the
same path as does the low tension between the com-
mutator and the coil.

The condenser is electrically connected between the
two contact points of the vibrator so that the induced
current of the primary will be absorbed on the break
of the contacts and given back to the primary winding
of the coil as in any other ignition system making use

FORD IGNITION 255

of a breaker. The condenser is connected with the
contact point on the stationary bridge of the vibrator
by the wires 6 and 8 and to the contact point on
the spring blade by the wires 3 and 9.

The construction of one form of Ford coil is shown
in Figure 105, the numbers being the same and
referring to the same wires as in the preceding Figure,
but in this case the parts are shown in the relative
positions that they occupy in the wood box which
encloses them. The terminals marked 2, 4 and 5 are
flat brass discs on the surface of the box and these
discs bear against three spring contacts which com-
plete the circuits to the outside connections when the
coil unit is in place in the housing which carries the
four coils. The box is filled with insulating com-
pound to hold the various parts in position. As will
be noted from the illustration, the primary winding
is carried for the entire length of the iron wire core
while the secondary winding is shorter and placed
around the outside of the central portion of the pri-
mary. The condenser is built up of waxed paper
and tin foil and is then folded into a compact roll.
Between the condenser and coil is a piece of glass
one-fourth of an inch thick which provides effectual
insulation for the high tension current.

The only adjustment of the vibrator is that con-
trolling the gap between the contact points when they
are opened. This adjustment is made by turning the
knurled nut D up or down on the screw G. Adjust-
ment may be necessary because of increase of this gap
due to wear or burning. Before making any adjust-
ment the contact points should be examined and
if they are found rough or pitted they should first be
filed flat with a very thin file. Tim cs^^'t^b5s2^<3^ ^«^s^

2S6 AUTOMOBILE IGNITION

also be performed by drawing fine emery elotb be-
tween the contacts while they are held together, first
with the emery side up and then down. After dress-
ing the contacts the adjusting nnt should be turned
Qutil, with the contacts held apart their full distance,

the points will be twenty-five thousandths of an inch,
or a little less than a thirty-second apart. E and F
are fibre washers which insulate the bridge A from
the adjuBtmg screw. The adjustment is maintained

FORD IGNITION 257

by the tension of the spring H acting Against the
threads of the nut.

COMMUTATOR

In the Ford ignition system the time at which the
spark occurs is determined by the commutator, which,
in one sense, takes the place of the breaker mechanism
of the usual equipment in timing the spark. From
the explanation of the action of the coil and vibrator,
it will be seen that the spark will pass at the plug
points as soon as the commutator roller touches one
of the segments and this musi; occur when the piston
of one of the cylinders in which the plug is located
reaches top center at the end of its compression stroke.

The Ford commutator, shown in Figure 106, con-
sists of a metallic roller attached to the forward end
of the cam shaft so that it turns with this shaft and
at one half the crank shaft speed of the engine. This
roller is carried inside of a circular housing made of
insulating material and into which are set four metal-
lic contacts or segments. TSe roller touches these
segments in turn as it revolves inside the housing. To
each of the four segments is attached a terminal or
binding screw which appears on the outside of the
housing and from each terminal a wire leads to one
of the coil units.

It will be recalled from the explanation of the action
of the engine that the cam shaft makes one revolution
for each two revolutions of the crankshaft and that for
each complete cycle of strokes in any one cylinder
the cam shaft makes one full turn. Bearing in mind
that the commutator roller is fastened to one end of
the cam shaft and taking any oive oi Wv^ Q,^\tt!K>:^'?iXss«^

AUTOMOBILE tQNITION

segments aa an example, it will be seen that the roller
will touch this segment once for each complete cycle
in one cylinder. Thus, for each power stroke in the
cylinder considered, there will be a complete circuit

FlBure lOfi. — Commutator or Timer of Ford Ignition System.

through the commutator, the coil and the ma^eto
and a stream of sparks will be produced at the plug.

The roller in the commutator is placed in such a
position on the cam shaft that it makes connection

FORD IGNITION 259>

with one of the segments each time that a cylinder i»
ready to fire and the segment with which connection:
is made is the one from whose terminal a wire leada
to the coil used with the spark plug of the cylinder
that is then ready to fire. The next contact in the
commutator with which the roller engages is connected!
with the coil whose spark plug fires the cylinder next
to deliver power and so on for all four segments and
all the cylinders.

WIRING AND TIMING

The external wiring and its connections through
the coils and magneto winding are shown in Figure
107. The coil terminals are shown as they appear
from the engine side of the dash and the commutator
terminals as they appear from in front of the engine.
The engine cylinders with their spark plugs are num-
bered from 1 to 4, number 1 being toward the radiator
and number 4 next the dash.

From the magneto terminal the primary current
passes through the switch when it is closed on the
magneto side to a common bus connection in the coil
box. This common connection carries the current to
the terminals on the bottom of the four coil units and
this bottom terminal leads to one end of the primary
winding. Inasmuch as the vibrators do not require
any additional outside connections or wiring they have
been omitted from the diagram. After passing^
through the primary circuit of the coil the current
leaves the unit by way of the upper terminal button
of the coil case and passes through one of the wires
leading to the commutator, just which wire depending
on which of the commutator segments the roller is
then in contact with. From the commutator roller

260 AUTOMOBILE IGNITION:

the primary circuit is completed through the metal
back to the magneto. The secondary wires to the
vspark plugs are attached as shown in the diagram;
that from number one cylinder leading to the coil
toward the right of the car (observed from the driver's
«eat), the wire from number two plug to the second
coil from the right and so on. The firing order of the
engine is cared for by crossing the wires between the
commutator and coil rather than the wires from the
<3oil to the plugs.

To properly time the commutator .the following
method may be used: First place the spark. control
hand lever, which is underneath the steering wheel,
two notches on the quadrant from its fully retarded
position. In the retarded position the lever is for-
ward or away from the driver and to make ready for
timing it should be moved two notches toward the
Tear of the car. The piston of number one cylinder
jshould then be brought to top dead center between the
-compression and firing strokes, this position being
determined by observing or feeling the rise of the
piston through the opening left by removal of the
«park plug. The cover of the commutator should then
be removed and the position of the roller observed.
This roller travels in a left hand or anti-clockwise
direction, that is, in a direction opposite to that of
the crank shaft. The timer housing should be moved,
without disturbing the position of the hand control
lever, so that the roller is just making contact or just
about to make contact with the segment attached to
the terminal at the left of the control rod lever, this
being the terminal used for firing number one cylin-
der. The roller should be found very nearly in this
position provided it is correctly attached to the end

FOBD IGNITION

262 AUTOMOBILE IGNITION

of the valve cam shaft and the slight adjustment that
may be necessary can be made by altering the length
of the control rod between the commutator and the
lower end of the steering gear rod, this alteration
teing either by the screw adjustment or by bending
the rod.

A wire should then be attached to the terminal
mentioned and run to the low tension terminal at the
upper end of the right hand coil, this being the ter-
minal in the upper row of four which is toward the
right hand side of the car. In case the colored cables
are used this wire for number one cylinder will be
black. As the roller turns in the direction it is driven
by the engine it will next make contact with the seg-
ment for the terminal just below the one already con-
nected and from this second terminal a wire (red)
4should be run to the upper coil terminal second from
the right hand side of the car. The' firing order of
the Ford engine is 1-2-4-3 and the wire (green) from
the next commutator terminal in the direction of rota-
tion will therefore be connected to the coil for num-
ber four cylinder, which is the coil toward the left
of the car. The remaining terminal will then be con-
nected by its wire (blue) to the coil for number three
•cylinder.

TROUBLES AND REMEDIES

In case of misfiring in one or more cylinders the
particular ones at fault may be located by manipula-
tion of the coil vibrators. The throttle should be
opened sufficiently to allow the engine to run at fair
speed and while thus running, the vibrator blades of
the two outside coils, number one and number four,
should he held with the finger tips. Number two and

FORD IGNITION 263

number* three cylinders are thereby allowed to fire
while one and four are cut out. If, from the sound of
the exhaust, it is found that two and three are firing
regularly the trouble should be looked for on either
number one or number four. While still holding num-
ber four vibrator, that for number one may be re-
leased and if the cylinder then picks up and fires reg-
ularly a similar procedure should be gone through
with by releasing number four and holding number
one. It will be finally found that the vibrator for one
or more of the cylinders may be held or released with-
out causing any change in tlie running of the engine
and it will thereby be known that the cylinder con-
nected with this vibrator which shows no change in
running is the one in which, or in whose connections,
the trouble exists. Having located the cylinder in
trouble its spark plug and coil vibrator should bo
looked to first.

The plug insulation inside of the shell should be
clean and free from soot, oil or moisture, the insula-
tion should be unbroken and the gap between the
electrode points should be very close to 1/32 of an
inch. It will also be advisable to clean the portion of
the insulator which extends outside of the cylinder
and shell. The spark plugs and high tension wiring
of the Ford are no different from those of any other
car and the general troubles to which these parts of
the equipment are subject should be checked accord-
ing to the general instructions on troubles and
remedies in Chapter Fourteen.

The vibrator should he examined to see that the
contact points are not worn, dirty, sticking or badly
pitted. If any of these conditions are ioww^ *C^^ ^'^'^-
taets should be dressed by drawm^ ^ ^\7c\^ ^"^ ^^^^'^

264 AUTOMOBILE IGNITION

emery cloth between them, first with the emery facing
up and then down. With the contacts in proper con-
dition the correct adjustment may be made by screw-
ing the adjusting nut up until the contacts are allowed
to separate. The nut should then be slowly turned
down until slight tension has been placed on the
spring blade or until the cylinder connected with this
coil foes regularly. It is possible that the coil unit
or the coil box have become wet, allowing a short
circuit, or that some of the connections inside of
the coil box have become loose.

With the vibrators adjusted, the coil unit for the
cylinder at fault may be lifted out of the box and
exchanged with another unit of a cylinder which is
firing properly. If this changes the misfiring to the
cylinder now connected with the coil which was origin-
ally connected with the first cylinder in trouble, the
trouble is evidently with the coil or its vibrator. The
defective coil should then be removed from the case
and tested as shown in Figure 108. Terminal A is
that through which the magneto current enters the
coil, terminal B is the high tension lead to the spark
plug wire and terminal C is used for the connection
to the timer wire and through this same wire for the
ground connection of the high tension winding of the
coil. With a wire held firmly on terminal C and with
its other end about one quarter inch from B, a spark
should pass across this gap to B whenever a six volt
storage battery or a battery composed of five dry cells
is connected and disconnected with terminals A and C
as shown. If, by changing the vibrator adjustment, it
is still impossible to secure a spark, the fault lies
within the coil or in the parts of the vibrator. If the
fault is inside the coil unit the most satisfactory

FORD IGNITION

265

remedy is the installation of a new unit because the
windings, the condenser and their connections are
imbedded in an insulating compound that makes the
work of repair inside the unit more costly in time
consumed than the price of a new coil and vibrator.

There are but few troubles that affect the Ford
magneto and in case it is determined that insufficient
current or no current at all reaches the coil box it
will be first in order to remove the terminal contact

Figure 108. — Testing Ford Coil Unit with Battery.

which is carried on top of the flywheel case. It may
be found that dirt has collected at the lower end of
this contact brush and with this foreign matter cleaned
away normal action will be resumed. If the car is
an old one or if the engine has recently been disas-
sembled and rebuilt it is possible that the permanent
magnets of the magneto have become weakened and
it will be found most economical to replace them with
new ones. The magnets should b^ ^^"&^\c^<fe<$ic '^rcs. *vi5sfe

266 AUTOMOBILE IGNITION

flywheel so that the negative polea of adjacent mag-
nets are together, this also bringing the positive poles
together, that is to say, magnet enda of like polarity
should be together in all cases. In assembling the
magnets the polarity may be determined by the use of

Figure 109.— Relative Poaltions of Parts

Top; Placing ot Magnet Poles. Lowei

Assembly on F'ly Wheel. Lower RlEht: Colls
Mounted on StatlonB.ry RIdk-

a compass, making sure to place two ends together
that both attract the same end of the compass needle.
A simple way to make sure of correct* assembling is
to bring the magnet ends close together while they
are off the flywheel and place together the poles or

FORI> IGNITION

26T

ends which do not tend to draw together. If two-
magnets are held in this way with one end of one
magnet close to an end of the other, it will be found
that the ends either have strong attraction for eack
other or else that they have no attraction or even ^ a
repulsion. The magnets should be placed on the fly*
wheel with the ends together which have no attraction,
for each other, the polarities then being as shown at
the top of Figure 109.

It is possible to remagnetize the permanent magneta
of the Ford magneto without disassembling them by

UDDOQEDD

I I
I I

^,^~' Tii^^ A <iw/5f /

C0/fP^SS

H/tttjf/fl€

Figure 110. — Recharging Permanent Magnets in Ford

Magneto.

the method explained and shown in Figure 110. The^
magneto coils are used as energizing electro-magneta
and with the permanent magnets in position so that
their poles are directly opposite the ends of the core»
in the coils the remagnetizing may be done by passing
a heavy current through the coils.

One of the coils in the magneto, the one from which
connection is made with the flywheel case terminal,
is about 1 1/4 inches to the left of the centre Ikas^
drawn lengthwise througTa. \Xie \.^Tm\xvaS. ^^^'^V. ^^>is^

268 AUTOMOBILE IGNITION

the battery connected as shown the current will flow
through the coils in such a way that the first coil to
the left of the center will be made an electro-magnet
with its positive pole toward the permanent magnets,
this being the proper relation of the electro- and the
permanent magnets for the operation.

To perform the operation it is first necessary to
secure an ordinary pocket compass and hold it near
the rear side of the flyivheel housing and with its
-center about ll^ inches to the left of the center line
of the engine which is known from the position of the
magneto terminal. "With the wire disconnected from
the magneto terminal and the compass in position,
«lowly crank the engine until the North pole of the
•compass needle points straight ahead as shown, this
indicating that the South or negative pole of a per-
manent magnet is directly in front of the compass and
therefore directly in front of the core of the first coil.
The' correct relation of all the parts is shown in the
illustration.

A direct current oi from twenty to thirty volts pres-
isure is required and this may be conveniently secured
by connecting four six-volt storage batteries in series,
•or any number of storage batteries or dry cells which
will deliver the desired voltage may be employed. The
positive terminal of the series of batteries should then
be connected with the magneto terminal on top of the
flywheel and a length of wire attached to the negative
terminal of the batteries. With the magneto parts
in the positions described, the end of the length of
wire from the negative terminal of the batteries should
be touched to the metal of the engine, held there for
not more than one or two seconds and then removed,
/IiJs operation of touching the metal being repeated

FORD IGNITION 269*

from ten to fifteen times. Each time the connection
is made and broken the engine will be felt to jar
noticeably, this being caused by the attraction between
the coils and the permanent magnets. This operation
will increase the strength of the permanent magnets
and if weakness was the cause of the difficulty a rem-
edy will be effected. The remedy is not, however, a»
satisfactory as that secured by replacing the old mag-
nets with new bnes.

If ignition trouble is noticeable only when running
at high speeds the commutator should be examined.
The surface of the circle around which the roller
travels should be clean and smooth so that the roller
can make good contact with each of the segments with
moderate tension on the coil spring. In case the clean-
ing of the commutator ring does not effect a remedy,
and if the fibre, the roller or the segments are badly
worn and show pitting, the most satisfactory remedy
will be to replace the defective parts with new ones*
It is assumed that the small coiled spring is strong
enough to maintain a firm contact between the roller
and segments under all conditions.

It may be found that the lubricant used in the com-
mutator has become thick or hard, this being espe-^
cially noticeable in cold weather. Such a condition
will prevent the roller from making good contact with
the segments, especially at low engine speeds and when
the car is first started. This trouble may be over-
come by using a lubricant composed of three-fourths
lubricating oil and one-fourth kerosene, or by using
any of the very light machine oils that are on the
market.

In examining the commutator se^^ ^XvaX. "Ow^i ^^S^^sc
is free to revolve on its pin .and l\va\. \Xv^ «x:^ ^"^"^"^

270 AUTOMOBILE IGNITION

not stick in any one position when moved by hand.
These difficulties may be removed by cleaning and
oiling and, if necessary, by increasing the tension of
the coiled spring. It is also possible that the roller
^rm or roller sleeve is loose on the forward end of
the shaft, this indicating play in the key or nut
ivhich holds it in place.

The wiring, both low and high tension, should be
examined for defective insulation, broken strands,
«hort circuits, accidental grounds and all of the
usual troubles found in the connections. The con-
nection of the wires between coil and commutator
«hould also be examined to make sure that they cor-
respond with the firing order of the engine and with
the connections shown in the wiring diagram.

MASTER VIBRATORS

In connection with the Ford coil an additional
coil consisting of only a low tension winding, a con-
denser and a well constructed vibrator may in some
cases be employed as a fitting attached after delivery
of the car. The connections and internal wiring of
such a device are shown in Figure 111. In making
the attachment the vibrators of the Ford coils are
rendered inoperative and the two parts carrying the
contact points are permanently connected, this being
accomplished by screwing the adjustment down tight,
or, preferably by attaching a short length of wire
such as a dry cell connector from the brass bridge
which carries the upper contact to the brass base
upon which is mounted the spring blade carrying the
lower contact. The current which formerly passed
across the contacts themselves will then take the path
through the length of wire and complete "ttie -^TAxxvaiy

FORD IGNITIOK

271

circuit through the coil at all times, regardless of
the position of the vibrator parts and contacts. Such,
a connection makes of the Ford coils simple induc-
tion coils with a high and low tension winding.

With the master vibrator connected in the ignition
circuit as shown, the primary current from the mag-
neto passes to one of the terminals of the vibrating
coil and to one of its contact points. From the other
contact point the primary current travels through

TS COffMi/r^T^^

the winding about the core of the master coil and the
ordinary vibrating action is set up. This pulsating
current then passes from the terminal of the master
vibrator to the primary winding of the four unit
coils, entering them through the terminal and path
formerly connected directly with the magneto. In
accordance with the position of the commutator the
pulsating current induces high teB,s\o'& \\Kif.'QN»&'«. "^b-
the seeondiary windings oi t\ve "PotS. ciAs, *iJt!ivs, «»x-

272 AUTOMOBILE IGNITION

rent being led to the spark plugs in the usual way.

The master vibrator is usually constructed with
its own switch, this switch being designed to con-
nect with the magneto as one source of current and
with an auxiliary storage battery or set of dry cells
as the reserve source. "With a switch incorporated
in the master vibrator the switch on the Ford coil
is allowed to remain in the position that makes con-
nection with the terminal (magneto or battery)
which has been connected with the master coil.

The advantage is using a master vibrator is that
the action in inducing the secondary current is of
necessity uniform for each of the four coils and the
adjustment once correctly made for the single
vibrator insures its correctness for each of the four
cylinders. The objection to the device is that the
additional resistance introduced by the additional
length of wire in the primary circuit reduces the
efficiency of the ignition, although with the surplus
of current generated by the Ford magneto this is
not in reality a serious drawback.

CHAPTER IX

MAGNETO IGNITION

The magneto as used for ignition purposes is »
simple form of dynamo having its fields formed by
permanent magnets and producing an alternating-
current of comparatively low voltage which ia
changed to a high tension current by means of an
induction or transformer coil canned either in the
magneto or as a separate unit.

The principle upon which a magneto of the arma-
ture type generates current may be understood by
reference to Figure 112. The parts shown at A.
include the horseshoe shaped permanent magnet M.
to whose extremities are attached the extensions P-P
called pole pieces. The inner faces of these pole
pieces are curved and between them rotates the iron
core B on the magneto drive shaft. On the core is
carried a coil of wire C and it is in this wire that the
current flow is induced. The coil and its core are
parts of the magneto's armature.

"With the armature in the position shown at A in
the illustration the magnetic lines of force from the-
magnet poles flow from the positive to the negative^
side, taking the path indicated by the arrows through
the center of the coil. As the magneto shaft is
rotated, the core and coil finally assume the position
shown at B. The lines of force still flow through the-
core, but because of the lessened siiri^a^ ^x^jsk^^^^

27a

274 AUTOMOBILE IGNITION

'to tiie face of the pole pieces, the flow has become
smaller. Further rotation brings the parts to the
position shown at C. Between B and C, the flow

of magnetism through the coil stopped and again com-
menced, but now in the opposite direction through
the core and the coil of wire. Between these last two

rigure 112. — Principle ot Current ' — -

Armalure. Top: Armature Posltlona. Bottom;
Corresponding Riae and Fall ol Voltagre.

points there has been an abrupt change in the intens-
ity of magnetism acting on the coil, in fact a com--
plete rcverKal has taken place. At the end of a half
revolution a second reversal takes place as the core
once more assumes a midway position between the
pole pieces and for each complete revolution of the
armature there arc two abrupt changes of magnetic
£ow through the core and coil. The rise and fall of

MAGNETO IGNITION 275

the voltage is shown by the curve in the lower part of
the illustration.

It was explained in Chapter Three that any change
of magnetism through the core of a coil would pro-
duce a flow of current through the coil. It will be
seen as a result of this fact that there will be two
separate flows or impulses induced in the coil for
each full turn of the armature of the magneto. One
of these impulses is positive and the other negative
in its direction of flow through the coil and connec-
tions, but for ignition purposes both are of equal
value and each is used to produce an ignition spark
or series of sparks, depending on the method
employed in the remainder of the equipment.

The action of the magneto is often explained
according . to the rate at which magnetic lines of
force are cut by the wires of the coil, or by the rate
at which the magnetic lines of force are traveling
relative to the coil wires. This method of explana-
tion is the same in effect as the one just given as will
be seen from reference to Figure 113. In the posi-
tion shown at A, which corresponds to A in the pre-
ceding Figure, the lines of force pass through the
coil as shown by the arrows and are cut through by the
coil wires at the least rate of any point in the revolu-
tion. It is at this point that the current value is
least as will be realized from the preceding explana-
tion for the reason that this position is just half way
between the current impulses.

Again referring to Figure 113 and position shown
at B, it will be seen that the wires of the coil are cut-
ting directly across the magnetic lines of force and
therefore that the greatest possible number est \xsns^^
are being cut in a given time. \\. \^ \w "Ckvs* ^«®J<nss^>

276

AUTOMOBILE IGNITION

corresponding to the point between B and C of tho
preceding figure that the current flow is greatest.

TYPES OP MAGNETOS

Two forms of construction are used in the manu-
facture of magnetos one of which, called the arma-
ture type, has just been explained and the other.

Figure 113. — Magneto Armature Coil Cutting Lines of Force
in Field. Top : Armature Positions. Bottom :

Change of Voltage.

called the inductor type, is explained in Chapter
Thirteen.

Transformer Coil Magneto. — This construction

includes an armature having a single winding of

rather heavy wire in which is generated a current of

low voltage which is sent through the primary cir-

MAGNETO IGNITION

277'

cnit. A transformer coil is carried as a separate
nnit and to this coil the primary current from the
magneto is led, where it produces a current of high
voltage passing through the high tension or second-
ary circuit and to the spark plugs.

The circuits of a typical transformer coil magneto,
the Remy Models P and 32, are shown in Figure 114.
It will be seen that one end of the armature winding
or coil is grounded to the core and from this point

O/tr C£LLS

CmSUIT BKEflKEIt

the ground circuit is complete to the metal parts of
the engine. The other end of the primary winding
terminates in a brass ring on which rides a brush.
The current flows to the ring, into the brush and
through the wire shown, to the terminal G of the
eoil unit. From this terminal the current pasai* ^
the switch, which is in thia case mo\m.\ad. Qtv '^^'a. ««^

278 AUTOMOBILE IGNITION

box. From the switch the current passes through
the primary winding of the coil (shown near the
bottom of the coil case) and then from the coil unit
terminal Y to the circuit breaker. With the breaker
contacts closed as shown the current passes through
them and to the metal of the magneto, going through
this ground connection back to the armature and the
grounded end of the winding. This completes the
primary circuit.

It will be noted that the condenser, in this case
mounted in the magneto, is connected* between one
of the breaker contacts and the ground so that it is
in effect placed across the breaker contacts in the
usual manner.

A second primary circuit using the dry cells as
its source of current is also shown. The ground con-
nection for one side of th^ dry cell circuit is obtained
through the line to the coil terminal B, through the
coil box to the terminal R and from there to the
ground. The other side of the battery is connected
through the second terminal B to the switch . and
through the switch to the primary winding of the
coil. From this winding the current flows by way
of the terminal Y to the circuit breaker and is
grounded through the breaker.

While the Remy instruments just described illus-
trate the application of the transformer coil type of
construction, it is of course possible to introduce
many variations in the details and the disposition
of the several parts. The condenser may be carried
in the magneto, or is quite often found in the coil unit.
The switch may be attached to the coil or may be a
separate unit, such a separation making additional
wiring eoi3i3ections necessary. A safety spark gap

MAGNETO IGNITION 279

is generally arranged at some point on the coil,
although it may be found in the magneto itsell

In a general way the wiring connections between
the magneto and coil are the same for all transformer
coil instruments in that there are three primary
wires and one secondary, the secondary leading from
one end of the high tension winding in the coil to-
the terminal connecting with the distributor rotor
on the magneto.

Of the three primary wires ; one makes connection
between the primary winding on the magneto arma-
ture and the primary winding of the coil, either
directly or through the switch; a second connects,
the primary winding of the coil with the insulated
contact of the circuit breaker, while the third pro-
vides a ground connection for one end of the primary
and one end of the secondary winding of the coil,,
also in some cases for one side of the auxiliary bat-
tery set. This method of connection may be noted
in Figure 159 showing the wiring diagrams for
Splitdorf transformer coil machines in which the^
wire between terminals A connects the magneto-
armature primary with the coil primary winding,,
the current from the coil primary returning through,
the wire between terminals marked 2 to the circuit
breaker on the magneto. The line from coil terminal
3 provides a ground connection for the high and
low tension windings of the coil and for^the dry
cells. This scheme of wiring applies to all similar
Splitdorf equipment.

True High Tension Magnetos. — The type of mag-
neto known as the true high tension does not utilize^
a separate transformer coil, but carries a secondary
winding on the magneto armatwi^ \o%^\X^fcT ^SJCg. "^ic^

280

AUTOMOBIL.B IGNITION

primary winding. The primary armature winding
then acts as the primary of the combination which
is, in effect, a transformer coil, and produces changes
of magnetism in the common core, which changes
induce the high voltage impulses in the fine wire
secondary winding. The difference between the two
armatures is shown in Figure 115 in which the upper
illustration shows the transformer coil type with the

f>R/M/lRY y^/r^DtnCf.

C^J9BO^a^USff

TO o/srf^tBuro^

/'^j^fM^^y Ao^Aia'A^

SEC Yf^rfOfrff^.

T'igure 115. — Types of Rotating* Armatures of Magnetos.

Top : Transformer Coil Type. Bottom : True High

Tension Type (Remy Electric Company).

«ingle primary coil on the armature core, while the
lower illustration shows the method of placing the
two windings on the same core. One end of the sec-
ondary winding is grounded through the same ground
that serves the primary winding and the other end
of the secondray attaches to a conducting ring on
which a carbon brush makes contact while the arma-
ture revolves. The high tension current passes

MAGNETO IGNITION

281

through this collector ring and brush and to the rotor
of the distributor on the magneto.

The complete connections of a typical high tension
magneto, the DU4 Bosch, are shown in Figure 116.
The two windings are shown on the armature core
and it will be seen that the secondary forms a con-
tinuation of the primary and grounds through the
primary. One end of the primary winding leads to
the insulated contact of the breaker and completes
its circuit to ground through the other breaker con-

, U fl

Magneto
Interrupter

Figure 116. — ^Circuits of True High Tension Magneto System

(Bosch).

tact. The condenser is carried in the end of the
armature and is electrically connected between the
breaker contacts.

The secondary winding terminates in a collector
ring and brush arid from this brush the current
passes through a conductor bar (not shown) to the
distributor rotor and from .the several distributor
segments to the spark plug lines. Such a magneto
requires but five outside wires for a four a^VvwAsssc
engine, four going to the plvig^ aivQi \Xvfe ^fi?Ca. "Ix^sc^.

2® AUTOMOBILE IGNITION

the breaker to a switch through which the primary
current may be grounded when it is desired to stop
the production of sparks in the plugs. Any high ten-
sion instrument requires one iine to each spark plug
and one additional line for the switch.

The constructional details of a typical high tension
magneto (Simms) are shown in Figure 117. This
illustration shows the design of the coUector ring

Figure 117. — Construction of Trui

with its brush holder, the conductor bar between the
i?ollectoi" brush and the center segment in the dis-
tributor, also the method of placing the safety spark
gap between the collector brush upper terminal and
the metal of the magneto framework

Dual Magnetos. — The word dual is somewhat con-
fused in its application to ignition apparatus because
of the fact that those tj'pea here described as trans-

MAGNETO IGNITION 283

former coil machines are often called dual magnetos.
We will, however, take the more generally accepted
meaning and define a dual magneto as a high*tension
instrument having two separate circuit breakers and
a separate transformer coil, one of the breakers being
used for the magneto primary current, while the
other is used only with the current from an auxiliary
battery and in connection with the transformer coil.
The separate coil is not used with the magneto pri-
mary current, this being unnecessary because the
magneto armature carries two windings and gener-
ates its own secondary current.

In the transformer coil magneto both battery and
magneto primary currents are handled through the
one breaker, one coil and one set of primary wires,
also through the one distributor and secondary sys-
tem. In the dual magneto the only parts common to
both sources of current are the distributor, the sec-
ondary wires to the spark plugs and the plugs them-
selves. The primary circuits are separate, as are
the breakers and coils. A more extended description
of this type will be found in Chapter Eleven.

Duplex Magneto, — The Bosch Magneto Company
has manufactured a type of ignition styled ''duplex''
which combines a battery circuit with any of their
high tension machines. The system includes the.
standard magneto and in addition, a battery and a
small outside coil which are used in conjunction with
the magneto. The battery side is not intended for
use as a separate ignition system but only as an
auxiliary to the magneto in starting.

With the battery in use the primary winding on
the magneto armature is included in the battery cir-
cuit, as is also the coil, and ttie \i^\X^T^ Qixx:t^^^^^ ^^j^S^a*

284 AUTOMOBIL.E IGNITION

its strength to that of the magneto which at very
low cranking speeds is not sufficient to produce a
spark. As the magneto produces an alternating cur-
rent which changes its direction of flow every half
revolution of the armature, it is necessary that the
battery current likewise be made to change its flow
every half revolution and for this purpose a small
two part commutator is carried inside the breaker
housing. A change in direction of the magneto cur-
rent is accompanied by a corresponding change in
the flow of the battery current. As soon as the engine
starts on its own power the magneto current is
stronger than that of the battery and the necessity
for the battery flow ceases. There is no noticeable
difference in operation whether or not the battery
is then in use.

The breaker housing cover consists of a fibre disc
held in proper position by a key and keyway. The
inner surface of the disc carries two metallic seg-
ments, each connected to a terminal on the cover,
and the breaker is provided with two brushes which
travel over the two segments when the armature
rotates. This construction provides for reversal of
the battery current. The coil unit contains a sim-
ple primary coil and the parts forming the switch.
The connections for this system are shown in Fig-
ure 118.

STARTER COILS

A large number of engines are fitted with a single

system of ignition provided for by a true high tension

magneto without an auxiliary battery system for

starting. Because of the circumstances existing,

such as poor grade oi fuel, size of the engine or con-

MAONETTO IGNITION

286

AUTOMOBILE IGNITION

ditions of operation, it is sometimes difficult to crank
the engine with sufficient speed to produce a spark
hot enough to ignite the mixture. To overcome this
difficulty means have been developed for attaching
auxiliary vibrating coils and battery sets to these
magnetos, these coils and batteries being used in con-
nection with the lAagneto breaker and distributor to
provide means for easy starting. These systems bear
some similarity to the duplex type just described
with the exception that a special breaker construction
is not required.

MAGNETO
STARTER COIL

Figure 119. — ^Principle of Operation of Starter Coil

(Ffanstiehl).

The principle of operation of a starter coil may be
understood by reference to Figure 119 which shows
the circuits of the Pfanstiehl unit. Following the
straight arrows, the current passes from the battery
to the vibrator and through the contacts which are
normally held together by the spring. From the
contacts the current passes through the coil and
around the core, thus magnetizing the core and
attracting the vibrator. This attraction causes the
contacts to separate, stopping the flow of current

MAGNETO IGNITION

until the spring again closea the contacts after the
magnetism has died out. This vibrating acUon con-
tinues &B long as the current flows. From the starter

—Wiring of Starter CoIIh. Top: With True High
lenaion Magneto. Bottom: With Tranatormer
Coil Magneto. (Pfanstiehl.)

coil winding the current passes to the magneto
breaker and through the closed bTftat^T *iOYftafc"«& ^»

288

AUTOMOBIL.E IGNITION

the ground, thence returning to the battery and
completing the circuit. Should the magneto breaker
contacts be open when the starter coil switch is
closed, they will be closed as soon as a part of a revo-
lution takes place in cranking, at which time the
above described action will commence.

As soon as the cranking operation opens the mag«
neto breaker contacts, the battery current can no
longer flow to ground through them and it then
passes from the insulated breaker contact to the pri-

/M£/I/C£A

MS/r/rsAi

JFigure 121.— Duplex Igrnition System with Vibrating StarteF
Coil. Left ; Insulated Battery. Hi£rht : Grounded Battery.

mary winding of the magneto armature. This
pulsating current through the armature winding
induces a current of high voltage in the secondary
winding, one impulse being given for each opening
of the starter coil vibrator and one spark produced
at the plug of the cylinder ready to fire. This stream
of sparks takes place as long as the magneto circuit
breaker contacts remain open, then ceases as they
close, and again takes place when the contacts re-open
^or the next cylinder to fire.

MAGNETO IGNITION 289

The connections of the Pfanstiehl coils to a high
tension magneto, also to one of the transformer coil
type are shown in Figure 120. Connections of the
Bosch vibrating duplex system, operating on similar
principles, are shown in Figure 121, the left hand
diagram showing an insulated return and that at
the right a grounded battery.

TWO SPARK IGNITION

Certain advantages have been found in providing
two simultaneous sparks at two separate points in
the combustion space rather than the single spark
generally utilized. Types of magnetos having dis-
tributors designed to accommodate two plugs in each
cyUnder are built and called two spark machines.
Wiring for one such Bosch instrument is shown in
Figure 122. The difference between this type and
the usual form is in the secondary circuit only,
neither end of the high tension winding being
grounded in the two spark instrument. The high
tension current induced in the secondary winding
flows to one of the distributors, or to one of the halves
of the single distributor, depending on the construc-
tion, and from there passes to the spark plug con-
nected with this distributor. Entering the plug and
passing across the gap, the current flows to the metal
ground of the engine and through this metal to the
shell of the second spark plug in -the same cylinder.
After passing across the gap in this second plug the
high tension current flows through Jhe spark plug
wire back to the second distributor to whose rotor is
connected the other end of the high tension winding,
thus completing the circuit between the wiaA\s\.^ ^>xn-^
the two plugs. No change is T^c3^\t%^\w *0^^^s^^^^'^

AUTOMOBILE IQNITION

79 SMmh.aas

UZAREST nSeCONaSET

InlttValves Of SpmuPuios

LomTensibnCi^ble

I i¥£r^i cr cyi//v^sjf | R

Figure 122.— Two Spark Ifrnltlon. Top: Wlrlnsr of BoBCb

Independent Magneto System. Bottom : Path ol

Current ju High Teoalon Circuit.

MAGNETO IGNITION 291

or in any of the parts of the primary circuit. A
schematic diagram of the high tension circuit ia
shown at the bottom of Figure 122.

The success of two spark ignition is largely depend-
ent on the location of the two spark plugs with
reference to each other. If they are close together,
as .for instance in the adjoining valve caps of an L
head engine, there will be little if any difference in
operation on one set of plugs or on both, for in either
case the flame must travel from one side of the cylin-

der to the other. If the plugs are located at widely
separated points, as for instance on the opposite
sides of the cylinder of a T head en^ne as in Figure
123, the difference will be marked because the flame
from either side must travel only half the distance
across the cylinder before complete ignition results.
With ordinary types of ignition, and to a lesser
degree with the two spark type, the time required
for travel of the flame through the mi-statft, ^las. -waSisi
it neeesssiy to cause tte sp&Tk: \j&l.*si:ft 'Ctv*. -sj^'^^wso-

292 AUTOMOBILE IGNITION

reaches upper dead center. This ignition advance
ranges between 15 and 45 degrees and in some cases
even more than 45 degrees is found necessary.

It is then obvious that if ignition is started by
two sparks occurring simultaneously at two points
in the combustion space, the time required for com-
plete ignition of the mixture will be reduce^d. With
properly designed two point ignition an increase of
power amounting to about 17 percent has been
secured.

The explanation given by the Bosch Magneto
Company of the reasons for this increase in power or
efficiency is as follows: The advance required with
single point ignition entails a loss of efficiency,
because, in the first place, the combustion space is
not of a minimum volume when pressure is produced ;
and, in the second place, because of the heat loss that
will result from the long contact of the burning
change with an unnecessarily large cylinder wall
surface. Further loss of efficiency may be traced to
secondary effects, such as thrusts due to the unfavor-
able angle of the connecting rod, the less homogen-
eous quality of the mixture, etc.

MAGNETS AND POLE PIECES

The great majority of magnetos are constructed
with their magnets shaped as shown at A in Figure
124, this being the U shaped magnet, although often

•called a horseshoe magnet. Two, four or six of
these magnets are used, depending on the type, size
and make of instrument. If two magnets are used,
they are placed side by side with both negative poles
on one side of the armature and both positives on

^he other. Some machines are made with two more

MAGNETO IGNITION

293

magnets superimposed on the first two, still, of
course, with all the like poles on on^ side. In some
cases six magnets are used, three side by side and
three more outside of the first set.

A few variations in magnet form have been intro-
duced by various makers from time to time, two of
which are shown in the illustration, the Heinze type
at B and the Mea cylindrical or bell shaped magnet
at C. The Heinze magnet is formed from a round
bar bent into shape and machined at the lower ends.
The Mea bell magnet is adopted as k part of the Mea
magneto's design which maintains the same relative

Figure 124. — Forms of Field Magnets. Left: "U" Shape.
Center: Heinze Type. Kight: Mea Cylindrical Magnets.

position between the armature and the magnetic field .
regardless of the amount of advance and retard. The
Mea armature is carried longitudinally in the space
within the magnet and the entire structure ; magnet,
pole pieces and armature, is rocked on the longitudi-
nal axis in advancing the time of sparking.

Pole Pieces. — It is desirable, and in fact necessary,
that the air space between the poles of the magnets
and the iron of the armature core be as small as pos-
sible because it is with diflBculty that the magnetic
lines of force travel through any great distance irt
the air, or outside of iron and «»\^^ >Occtwi.^ ^jsk^ 'cJCs^sst

294

AUTOMOBILE IGNITION

substance. To reduce this space the polar extremi-
ties of the magnets are fitted with pieces of iron
called pole pieces, one side of these pieces being
securely held against the surface of the magnet's
poles, while the other side is shaped to form a recess
within which the armature revolves and which is
called the armature tunnel.

The application of the ordinary form of pole
pieces and the position of the armature core in the
tunnel is shown in Figure 125. It has been explained
in the foregoing portions of this chapter that the
most powerful flow of current is secured at the

Figure 125. — Pole Piece Construction and Armature Position
for Advanced (left) and Retarded (right) Spark.

instant the flow of magnetic lines of force reverses
in the core of the armature, this being the position
shown at the left in the illustration just as the rear
edge of the armature core leaves the edge of the pole
piece, the gap at this point being indicated in the
drawing. It is at this time, and with the parts in
this position, that the spark will be most powerful
and this position corresponds to full advance on the
magneto timing device.

MAGNETO IGNITION 295

If the spark is retarded it will occur later in the
stroke and the magneto armature, being driven posi-
tively from the engine, will have traveled a consider-
able distance from the point shown at the left. The
position of the armature core with reference to the
pole* pieces with the spark fully retarded will be
somewhere between the point of greatest current
flow and the point shown at the right of the figure,
in which the magneto flow has again been established,
but in which i:he value of the current is much
reduced. It is for this reason that the spark obtained
from a magneto of this type with the spark retarded
is weaker than at a more advanced position and it
is also for this reason that it is generally necessary
to advance the timing lever from one half to two-
thirds of its travel while the engine is being cranked.

To overcome this condition and to provide a spark
of more nearly uniform value over the entire range
of timing, some makers of ignition apparatus have
adopted pole pieces of special forms which are
designed to distribute over a greater range the time
during which a powerful spark is secured. One of
these special forms is shown in Figure 126, this being
the type used on some models of Eisemann magnetos.
The most extended portion of the pole pieces is
opposite the center of the armature winding and the
flow of magnetic lines of force is drawn from the
extremities of the pole pieces toward the center of
the core, theoretically sending a greater number of
lines of force through the armature core and coil.

Another special form of pole piece is shown in
Figure 127, this being the Simms type which would
tend to continue the flow of lines of force between
the position shown in full lme» ^tvSl \JftaX. ^o^^ra. \si.

296 AUTOMOBILE IGNITION

dotted lines, that is, over the entire range from fall
advance to full retard. With the breaJter opening
at the fully retarded position the gap between the
edge of the armature core and the edge of the pole
piece is one millimeter, while with the breaker open-
ing in the fully advanced position the gap between
armature core and the second edge of the pole piece
is likewise one millimeter.

With pole pieces of the ordinary form, the voltage

Figure 126.— Extended Pole Pieci

in the primary winding of the armature risee some-
what abruptly to a peak, as shown by the curves in
the lower part of Figures 112 and 113. Before this
peak is reached, the pressure is comparatively low;
and likewise, after the maximum point has been
passed, the pressure becomes rapidly less. In order
to produce a hot spark, it is necessary that the breaker
open very nearly at the instant that the greatest pres-
sure occurs.

With the various forms of extended pole pieces, the

MAGNETO IGNITION 287

effect is to flatten the top of the curve; the voltage
then never rises quite as high as with the plain pole
piece construction, but does maintain its greatest
pressure during a considerable number of degrees of
armature rotation. If the breaker contacts separate
at any point along this flattened top of the voltage
curve, a hot spark will then be produced.

Figure 127. — Extended Pole Pieces and Position of Armatur*

When €park 1h Advanced (full lines) and.

Retarded (dotted lines).

MAONBTO BREAKESS AND DISTBIDUTORS

Magneto Circuit Breakers. — The general construe*
tion and principles of operation of magneto breakera
do not differ form those described for battery sys-
tems in Chapter Pour. The magneto breaker is car-
ried at one end of the armature shaft and is operated
at the same speed as the armature shaft. "With the
exception of one or two makes but little used, the
magnetos all produce two corteiA \m^-vsSsK6 ^"^-^ ''^'^

298 AUTOMOBILE IGNITION

sparks for each full revolution of their armature.
Therefore, since the breaker must open once for each
Bpark, it must open twice during each revolution of
the armature. It is for this reason that magneto
breakers are fitted with two point cams for all
^igines having four or more cylinders rather than
with a cam having a number of lobes corresponding
to the number of cylinders to be fired as with battery

riKUre 12S.— Typical Magneto Breakur with Statlonarr Cam*.

While the battery types of breakers are so con-
Btrueted that the cam rotates and the arm and eon-
tacts remain still, a large number of magneto break-
ers are so made that the cams are carried in the '
breaker housing and remain stationary while the arm
and contacts are mounted on a base plate carried by
the end of the armature sliaf t and which according^
jvvolvea.

MAGNETO IGNITION 299

A breaker, of this type is shown in Figure 128.
The two cams may be seen around the inside of a
housing which remains stationary except for the
small movement required in advance and retard of
the spark. The other parts shown, including the
fixed contact on its adjusting screw together with
the arm carrying the moving contact, are mounted
on a base which is rotated by the magneto shaft
The breaker arm is pivoted near its center and under-

neath the small flat retaining spring shown. At one
end is the contact point and at the other a fibre
block which, during rotation of the base, strikes
alternately first one cam and then the other. This
action opens the contacts twice during each revolu-
tion of the armature.

A form of breaker used with Tsv*sp*\t» ^xA^^a^i-sss^
the revolving earn is shown, m ■FK^osft "VL^ • "^"^ ^

300

AUTOMOBILE IGNITION

be seen that, but for the cam having only two lobes,
the construction is jiractically the same as the battery
types.

Distributor Construciion, — The magneto dis-
tributor is generally located just above the breaker
mechanism and is driven by two gears at one-half,
three-quarters or full armature shaft speed depend-
ing on the number of cylinders. One gear is on the
armature shaft and the other carries the rotor of the

Figure 130. — Typical Construction for Magneto Distributor.

distributor, the distributor gear being larger in size
than the armature shaft gear. These parts are shown
in Figure 130. High tension current from the sec-
ondary winding of the coil or the armature is brought
to the central metallic plate C which is carried in
the cover of the distributor. The rotor K is carried
by the large gear and makes electrical connection

MAGNETO IGNITION 301

between the central plate and the segments S, of
which there is one for each cylinder to be fired.

Another form of distributor is shown in Figure
131, the distributor cover carrying the brushes which
take the place of the segments in the preceding figure.
The cover is illustrated at the left and the rotor mem-
ber which is carried by the large gear is illustrated at
the right. This form is used on a true high tension
magneto (Eiaemann) and it carries the collector
brush in the lower part of the distributor cover.
This brush rides on the collector ring and takes the

FlKu:

of Wipe Contact Typ»

high tension current from the armature to the central
brush of the distributor cover, from whieb it entera:
the rotor segment and is carried in turn to the
brushes connected with the spark plug wires. While
the two forms of distributors just shown are botit
of the wipe contact type, many magneto distributors
are made of jump spark construction in which the
Beeondary current passes from the rotor across a
minute gap to a aeries of pins or Be@£k.^ci^». w*- xsJoi
the insulating material oi ftie <ioNet.

)■

302 AUTOMOBILE IGNITION

Distributor Setting, — It will be noted that in the
construction of all distributors either the rotor or
the segments with which it makes contact provide
for a considerable length of contact. This is neces-
sary because the time during the revolution of the
armature shaft and the distributor rotor at which
the high tension impulse passes through the dis-
tributor varies with the degree of spark advance
being employed. If the rotor just matched the seg-
Inent the spark current would pass successfully with
the timing device for the breaker in only one posi-
tion, but, should the point of sparking and breaker
opening be changed, then the spark current would
pass either earlier or later and the distributor rotor
would not be in full contact with the segment for
the cylinder to be fired.

On most magnetos it will be found that the small
gear on the armature shaft carries a mark near one
of the teeth and on the distributor gear will be found
two marks at different points, either of which may be
made to register with the one on the small gear. One
of these marks on the distributor gear will be marked
L or **Left," while the other will be marked K or
''Eight." If the magneto is designed for right hand
or clockwise rotation (when looked at from the
driven end), then the distributor gear mark R should
be registered with the mark on the armature shaft
gear, while if the machine is for left hand or anti-
clockwise rotation, looked at in the same way, then
the mark L should be registered.

With these markings properly set with reference

to the rotation of the magneto it will be found that,

with the timing lever fully advanced, the distributor

j'otor Is just coming into contact with one of the

MAGNETO IGNITION

303

segments when the breaker contacts start to separate.
If this relation is not found to exist, then the setting
of the gears should be changed so that it is made
correct. In Figure 132 are shown three relations of
the rotor and segments, two of which are wrong (A
and B) while the third, C, is correct. If the proper
relation is not secured between these parts severe

Figure 132. — Relation of Rotor and Stationary Contacts in
Magneto Distributor. A and B: Incorrect Setting.

C: Correct Setting.

burning and pitting will result and the effectiveness
of the spark will be seriously impaired.

The high tension circuits of magnetos are pro-
tected by a safety spark gap which may be found
located in the distributor, at the collector ring, under-
neath the arch of the magnets or on the coil, depend-
ing on the type and make of instrument considered.

CHAPTER X
MAGNETO TIMING, WIRING AND DRIVE

The principles and general procedure of ignition
timing, as described in Chapter Six, apply in a gen-
eral way to the timing of magnetos, while many of
the details required lor the proper handling of well

known makes are described in Chapters Eleven,
Twelve and Thirteen, /

In the first paragraphs of the preceding chapter,
and in Figures 112 and 113, it was shown that the

MAGNETO

time of greatest current intensity oeeurs as the mag-
netic flow reverses through the core of the armature.
This position, is shown for clockwise and for anti-
clockwise machines in Figure 133, The setting of
the armature is determined by the dimension "e" and
the proper measurements at this point are given in.
Chapter Eleven,

The gears attached to the armature shaft and to
the distributor are so meshed that the distributor

Figure 1!4. — Armature Position in Belatlon to Breaker

Opening and Setting of Dlstrtbutor

CSplltdort Electrical Company),

rotor is in contact with one of the segments leading'
to the spark plug wires. The breaker cam is so
placed that the contacts separate with the armature
in the most effective position and the proper rela-
tions between armature position, breaker opening and
distributor contacts must be maintained for correct
operation.

The proper relation between the parts, tosk^'sc^
as obtained in a Splitdori -maKtvatQ wfe ■5w;s^«^""«

306

AUTOMOBILE IGNITION

Figure 134. It will be seen that just as the arma^
ture core has left the pole piece by a gap of 1/16
inch, the breaker contacts are about to be opened by
the cam on the armature shaft and the distributor
rotor is making contact with one of the segments.
The settings are shown for both left and right hand
machines and it should be noted that the timing arm
is in the fully advanced position in both cases.

It has been explained in a foregoing chapter that
ignition timing is generally done with the breaker
fully retarded, but the same results may, of course,

Figure 135. — Relation of Piston Travel to Degrees of the

Circle. ^

be obtained by timing with the parts fully advanced.
The maximum advance required is generally meas-
ured in degrees of the circle on the fljrwheel of the
engine. The flywheel rim could be divided into 360
degrees and any amount of advance or retard could
then be specified by mentioning the distance around
the rim either before or after top center of the piston
travel. By reference to Figure 135 it may be seen
that the piston travel up and down, measured in
inches, is not in direct proportion to the measurement

MAONETO TIMING AND DRIVE 307

in degrees around the rim of the flywheel. For the
first 15 degrees of flyivheel travel the piston moves
but a very short distance. During the next 15 degrees
the distance of piston travel is much greater while
from 30 to 45 degrees there is another increase and
so on until the 90 degree mark, or one fourth of a
revolution is reached.

In some cases the degree of advance is mentioned
in fractions of an inch of piston travel, while in
others it is mentioned in degrees of the circle around
the flywheel. Either of these measurements may
be translated into the other by means of .a simple
diagram shown in Figure 136 which is furnished by
the Bosch Magneto Company and explained by them
as follows :

The relation of the piston travel to the rotation of
the crank shaft depends on the stroke and the length
of the connecting rod.

The piston travel of an engine is easily determined,
and the determining of the rotation of the crank
shaft in degrees, corresponding to any desired pis-
ton travel, may be ascertained from the accompany-
ing diagram. In this diagram the relation between
the crank and the connecting rod length is as 1 :4.5.
In the diagram the vertical lines numbered at the
bottom give the stroke of the engine in inches, the
rotation of the crank shaft in degrees being indi-
cated by the slanting lines and the figures at the
right. The figures on the left and the horizontal
lines indicate the piston travel in inches. As an
example in the use of the diagram it may be desired
to find the piston travel for an advance of 30 degrees
on an engine of 6 inches stroke. The vertical line
for the desired stroke may b^ \dew\jAfeftL\>r3 *C;w^ ^^xt^^

308 AUTOMOBILE IGNITION

at the bottom of the diagram, and this vertical line,
**a," may be followed upward until it cuts the diag-
onal line at **e/' indicating the desired number of de-
grees which is 30 degrees in the present case. The
horizontal line, **b," nearest this point should be fol-
lowed to the left and in the present instance it will be
seen to indicate about 1/2 inch. This figure of 1/2
indicates the advance in inches of piston travel cor-
responding to a rotation of 30 degrees of the crank
shaft. Knowing the piston travel in inches and the
stroke of the engine in inches the intersection of the
horizontal line for piston travel with the vertical line
for the stroke could be found and a diagonal traced
toward the right from this intersection to the column
showing the advance in degrees.

MAGNETO DRIVE

Except for a few types of inductor machines all
magnetos are so constructed that they deliver two
sparks for each full turn of their armature shaft.
Four cycle engines require one spark during each
twp revolutions of the crank shaft for each cylinder
of the engine. A four cylinder engine will then
require four sparks during two revolutions of its
crank shaft, or two sparks for one revolution. A six
cylinder engine will require six sparks in two revo-
lutions and three sparks in one. An eight cylinder
engine, according to the same principle, will require
four sparks during each crank shaft revolution and
a twelve cylinder engine will require six.

The magneto producing two sparks for each arma-
ture revolution must, therefore, be driven on a four
cylinder engine at crank shaft speed because such
an engine requires the two sparks produced in this

MAGNETO TIMING AND DRIVE

J 'i

•S %

r '^

'■

■

„

S H

„

—

3 3» 4 4>i 5 S« 6 6>S 7 711
Srroke 1r incfaes.

40
35
30l

310 AUTOMOBILE IGNITION

one crank shaft revolution. Similarly a magneto on
a six cylinder engine must be driven at 1 1/2 times
crank shaft speed, on an eight cylinder engine at
twice crank shaft speed, and on a twelve cylinder
engine at three times crank shaft speed.

While some few magnetos are driven from the
engine by means of silent chains the great majority
are driven by means of gears meshing with the tim-
ing gears on either the crank shaft or cam shaft of
the engine. In the latter case the magneto is mounted
on a base formed as a part of the engine crank case
and the armature shaft of the magneto is connected

Flgrure 137. — Oldham Coupling.

with a shaft driven from the engine gears by some
form of coupling.

One of the first used couplings, that known as the
Oldham, is shown in Figure 137. This coupling
consists of three parts, two metal discs having grooves
which engage raised keys at right angles on the
opposite faces of a center member. One of these discs
is attached to the armature shaft of the magneto,
while the other is connected with the driving shaft of
the engine. While the Oldham coupling is preferable
to a straight shaft drive it leaves much to be desired.
jA satisfactory magneto coupling diouLd be flexible,

MACNETO TIMING AND DRIVE

that is, it should allow for a certain amount of axial
or angular displacement of the driving shaft and the
magneto armature shaft. It may also be found ad-
vantageous to have the bearing provide somewhat of
a cushioning effect A magneto coupling should also
be adjustable, so that a certain amount of timing may-
be accomphshed by this means A satisfactory coup-
ling should have good wearing surfaces and should
be easily taken apart, so that the magneto may b»
removed from its base without trouble Many eoup-

FlETure 13S. — Flexible Coupling for Magneto Drive

lings have been developed embodying several or all
of these desirable features.

A coupling made by the Eisemann Magneto Com-
pany is shown in Figure 138. The driving member
carries two sets of flat steel springs at whose outer
ends are mounted buttons which provide a bearing
surface. When in the driving position this member is
engaged between two blocks mounted upon a disc
forming the second part of the coupling. This diae
is composed of two plates ^iid^ \s«j,eSK«t \i^ \>f3»ak

AUTOMOBILE IGNITION

passing through slots. With ttese bolts loosened
one of the discs may be turned with reference to the
other and the timing thus changed.

JlUi

E^8;u^e 139. — Flexible Coupling for Magneto Drive <Bosob),

The parts of the Bosch coupling are shown in
Figure 139, It consists of a cone-shaped piece of
steel attachable to the armature shaft, terminating in

MAGNETO TIMING AND DRIVE 313

a rim having diametrically opposite fibre lined slots.
To the driving shaft is secured a flange that carries
a flat cross-bar consisting of a large number of fine
spring steel plates or leaves. The cross-bar fits in
the slots of the cone-shaped mediber.

This laminated cross-bar has a marked spring
action and permits the two members of the coupling
to have a slight relative torsional movement, which
is ample to absorb the shock of the varying resistance
to rotation of the magneto armature. Furthermore,
the spring cross-bar has a slight bending or twisting
movement sideways, permitting the two shafts to be
slightly out of line. With a rigid coupling both
driving shaft and magneto shaft must be in absolute
alignment and the shock caused by the magneto
resistance is transmitted to the driving gears.

A coupling made by the Westinghouse Electric &
.Manufacturing Company consists of two cup shaped
steel discs having their ^uter edges formed into a
series of fine teeth. With the discs pressed together
and with the cupped portions facing each other the
teeth may be engaged so that one part will drive the
other. The timing may be easily changed with such
a coupling and it also allows for a certain amount
of misalignment.

A commonly used form of coupling is shown in
Figure 140. This type consists, as in most of the
others, of two discs, one attached to the magneto
armature and the other to the engine driving shaft.
Between the two discs is a flexible member of leather
of or rubber impregnated fabric. This flexible part
is attached to one of the discs at two diametrically
opposite positions and to the other at two points
between the first two.

314

AUTOMOBILE IGNITION

A form of coupling designed to allow variation in
the timing consists of two flat circular plates, each
having a series of holes drilled in a circle near its
outer edge. These two plates are fastened together
by two bolts passing through the holes. The holes
are unequally spaced,^ so that the distance between
those at one point is greater than at another point.
With the fastening bolts removed from any two pair
of holes in which originally found, one of the plates
may be turned a greater or less distance with refer-
ence to the other and in this new position the bolts

Figure 140. — Flexible Disc Type of Magneto Coupling.

may be replaced in different holes which will then
be found in alignment.

STARTER COUPLINGS

Because of the fact that a magneto will not produce
s. spark across the plug gap at very low speeds and
because engines of large size cannot readily be
cranked at speeds great enough to produce a satis-
factory spark, a device known as the starter coupling
has been introduced.

The starter coupling, or as it is sometimes known,

the impulse starter, is so constructed ttat during a

/?art of each revolution of the shaft driving the mag-

MAGNETO TIMING AND

316 AUTOMOBILE IGNITION

neto, turning of the armature shaft is prevented by
a pawl. During this time the continued rotation of
the driving shaft compresses a spring which is a
part of the starter coupling. Just as the engine
reaches one of its firing points, the spring is released
and the armature shaft is given a quick impulse and
turns much faster than the driving shaft until the
original relation between the two is restored. This
impulse occurs during the time that the breaker
points separate and the result is a hot spark regard-
less of the cranking speed.

The construction of one form of starter coupling
(Sumter) is shown in Figure 141. At A is shown
the coupling assembled on the magneto. At B is
shown the interior of the cam member. At C is
shown the exterior of the cam member and at D the
end plate of the magneto with the stationary part of
the coupling in place.

When the engine is to be cranked the pawl is
thrown into its operating position by means of a
small plunger. The pawl engages the cam portion
of the coupling and prevents movement of the arma-
ture shaft. The cam member continues to revolve
and the long coiled spring is compressed. The driven
member of the coupling continues to rotate until
the cam with which it is integral reaches the pawl.
This cam forces the pawl out of the notch, the com-
pressed spring expands and the magneto armature
shaft is forced forward at a speed corresponding to
several hundred revolutions a minute. The short
cushion spring shown at B absorbs the shock and
brings the rapidly moving armature shaft to a gentle
stop.

The shape of the pawl and of the notch is such

MAGNETO TIMING ANT* DRIVE

817

that when the engme reaches a speed of from 200 to
250 revolutionB per minute the pawl is thrown out-
ward with soeli force that it is caught and held in
the inoperative position. In another type of Sumter
coupling the impulse device is automatically thrown
into and-out of engagement. The action of the coup-
ling automatically retards tlie spark for starting and
the impulse spark is several degrees later than the
normal retard position of the magneto. With th©
engine running normally the coupling makes no dif-
ference in the time of the spark, whether the timing
lever of the magneto is advanced or retarded.

Figure 142.— Impulse

(Teasle).

The Teagle impulse starter is illustrated in Figure
142. The action of this starter is as follows: As
the engine turns over, the member A is turned around
by the driving shaft and moves the member B with
it through the pressure of the spring C. The member
B is rigidly connected to the magneto shaft. When
the notch on member B reaches the top, the pawl D
drops into the notch and stops the movement of B.
The member A continues to moNt s«A wtK^-^-fssRs- '^^'^

318 AUTOMOBILB IGNITION

spring C. When the member A has moved far enough
to bring the side B against the pawl D, the pawl is
forced out of the notch and the force of the com-
pressed spring drives the member B and the attached
magneto shaft forward at a high velocity giving a
very intense spark. As the engine picks up speed,
E forces the pawl D out so far that it is carried past
dead center and remains out until pulled in by hand,
preparatory to starting the engine again.

The design and proportion of the impulse starter
is such that when the pawl is operating, the spark
occurs on dead center, thus obviating danger of back
fire. When the pawl is thrown out as the engine picks
up, the spark automatically advances about 25 de-
grees, thus giving the most efficient operating engine
condition without further attention of the operator.
In starting the engine, the operator should be sure
to pull the lever F upward, which automatically
throws the pawl D into engagement.

The action of the Eisemann starter coupling may be
understood by reference to Figure 143 ; in which, at
the left, is shown the device when ready for cranking,
and at the right when in the running position. The
mechanism consists of five essential parts; a housing
H which is attached to the magneto armature shaft ; a
driving member C which is driven from the engine;
a spiral spring S which is hooked to members H and
C ; a floating member or trigger T ; and a fixed bar B
which is mounted on the base of the magneto.

When the engine is cranked, the trigger T drops
by gravity, engages with the bar B, and thus tem-
porarily prevents rotation of the housing H. As the
cranking continues to turn the member C, the spring
S is wound up until the cam at C strikes the wedge W.

MAGNBTO TIMING AND DRIVE 31&

This forces the trigger upward until it slips off the
lower bar ; thus releasing the housing H and allowing
the tension of the spring to give the armature shaft a
quick impulse during part of a turn.

It will be seen that, after the release and as shown
at the right of the figure, the armature shaft is pre-
vented from being thrown past the normal position
by stops which are provided on the housing and on
the outer part of member C. It will also be noted
that member T is heavily overweighteil on its upper

Blgbt: RunniDg- FoeTtlon.

half, BO that the action of centrifugal force on this
counterweight draws this member toward the center
until a tooth enters the notch N on the driving mem-
ber C. The trigger is held in this position as long as
the engine operates, the notch giving a positive drive
for the magneto, independently of the spring.

Should the starter be rendered inoperative for any
reason, an emergency locking device may be engaged
as follows : Turn the engine until a heavy scratch
mark, to be found on the edge of the driving member
C, comes to the top. Then rotate the housing K as

320 AUTOMOBILrB IGNITION

far as possible in the normal running direction, or
until the hole for the trigger comes opposite the
scratch mark. In this position the trigger should
drop into its running position. The screw which
fastens the small locking plate should now be loos-
ened, the plate swung parallel to the center line of
the magneto, and the screw securely tightened again.
The locking plate will now prevent th^ trigger from
engaging with the notched bar B and the starter will
act as an ordinary coupling.

Oiling of this coupling is necessary only about
once in two years use ; and then only a light, non-gum-
ming oil should be used. Under no circumstances
should the internal mechanism be oiled with a heavy
cylinder oil or packed with grease, as such a procedure
would immediately put the device out of action.

MAGNETO MOUNTING

A magneto should never be mounted upon either
an iron or a steel base because in this case the metal
of the base would form a conducting path for the
magnetic lines of force between the two poles of the
field magnets. This would then form an easier path
than that through the magneto armature with the
result that the current generating properties of the
machine would be almost, if not quite, destroyed.
Satisfactory magneto bases may be made from alum-
inum, brass or bronze because all of these are non-
magnetic.

The correct position of a magneto upon its base is
generally fixed by means of dowel pins set either into
the magneto or the base. The magneto is then held
securely in place either by means of bolts passing

MAGNETO TIMING AND DRIVE ' 321

through the base and into the frame work of the
magneto or by means of one or more metallic stl'aps
which form clamps attached to the base and passing
over the arch of the magnets.

Some of the measurements and dimensions of mag-
netos, which have a bearing on the problems of mount-
ing and drive, have been standardized by the Society
of Automotive Engineers. They are given below, in
inches and millimeters; measurements applying to
four, six, eight and twelve cylinder instruments, ex-
cept as specified in the footnote.

MUll- .
Inches meters

Shaft height from base 1.771 45

Distance from center of front base plate

holes to large end of shaft taper 2.086 53

Distance from center of front base plate

holes to center of rear base plate holes. . 1.968 50 ,

Distance between centers of base plate

holes, left to right 1.968 50

Distance from large end of taper to end of

engine driving shaft « 1.625

Large diameter of taper ? 0.590 15

Small diameter of taper 0.472 12

Length of taper , 0.590 15

Length of thread 0.5905 15

Thread, U. S. S.— %" diam., 16 threads.

Diameter of engine driving shaft 0.750

Woodruff key in armature shaft, No. 3....%"x%''

Woodruff key in engine shaft, No. 8 %''x5/32*'

Base plate holes — %" diam., 16 threads.
Taper — 1:5, included angle IV 30* (approx.)

Timing lever radius , 2.125

Timing lever plain hole bore 0.250

Timing lever tapped hole — ^", 28 threads.

Magneto space height (maximum) 8.000 203

Magneto space length (maximum) 10.000 254

Magneto space width (maximum) 5.000 127

Note: For eight and twelve cylinder engines the shaft
height is 1.968'' and the maximum height is 9.000''.

322 AUTOMOBILE IGNITION

Care is generally exercised by engine designers
in locating the magneto so that it is some distance
from the carburetor or preferably on the opposite
side of the engine. This is because of the danger
of stray sparks igniting the vapors. It is also best,
when possible, to place the magneto out of the way
of any great heat radiated from the exhaust piping.
Other items affecting the location are convenience
in adjustment, inspection and removal of the entire
magneto or of any of its parts.

CHAPTER XI

HIGH TENSION JSIAGNETOS
DU TYPE BOSCH MAGNETOS

All Bosch instruments are of the true high tension
type having both low and high tension windings on
the armature and operating as complete self con-
tained units without the addition of outside coil»
or other parts except the spark plugs, the plug wires
and a simple grounding switch. These magnetos are
usually employed as the sole source of ignition al-
though they may be fitted in connection with an
entirely independent system having its separate set
of plugs.

The armature winding is composed of two sizes
of wire, one size comparatively heavy and the other
very fine, the heavy wire constituting the low tension
or primary and the fine wire the high tension or
secondary circuit. The rotation of such an arma-
ture between the poles of powerful permanent mag-
nets induces pulsations of current in the primary
winding and in this circuit is the circuit breaker.
The high tension current thus generated passes to a
ring at one end of the armature and is collected by
a brush in contact with the ring, being then sent
to the distributor to which the spark plug wires are
attached. The relation of these parts to each other
and the electrical connections are shown in Figure 116.

The beginning of the armature primary circuit is

323

324 AUTOMOBILE IGNITION

in metallic contact with the armature core and the
other end of this winding is connected by means of
the breaker fastening screw to an insulated block
on the breaker base which supports one of the con-
tact points. The breaker arm, carrying the other
•contact point, is mounted on the breaker base and
is connected or grounded through the metal with
the armature core. The primary circuit is complete
whenever the two contact points are together and is
broken by the end of the breaker arm coining in
contact with one of the cams carried in the breaker
housing or shell.

The armature high tension circuit is a continuation
of the primary, the beginning of the secondary wind-
ing being connected to the primary, while the other
end of the secondary leads to the insulated ring called
the slip ring which is mounted on the armature just
inside the end plate at the driving end. The detailed
construction of the magneto is shown in Figure 144.

The slip ring brush receives the high tension cur-
rent and by means of the connecting bar underneath
the arch of the magnets this current is carried to a
metal contact in the center of the distributor cap or
plate. Prom this center contact the current passes
to the distributor brush which is carried by a holder
mounted on the distributor gear and which conse-
quently rotates with the gear at one-half armature
speed.

Metal segments are imbedded in the distributor
plate and as the brush rotates it makes contact suc-
cessively with the segments in the plate. The seg-
ments in turn are connected with terminals on the
outside face of the plate and these terminals are con-
nected by wires to the spark plugs in the several

HIGH TENSION MAGNETOS 325.

326 AUTOMOBILE IGNITION

cylinders. The high tension current passing across
the gap between the spark plug electrodes produces
the ignition spark and then returns by the metal
ground connections to the magneto armature core,
thus completing the secondary circuit.

In order to protect the armature and other current
carrying parts a safety spark gap is arranged on the
dust cover above the armature. This gap consists
of two small, pointed electrodes supported a short
distance from each other. One electrode is set on
the dust cover itself and is enclosed by a metal hous-
ing with a wire gauze screen for the prevention of
-accidental fires in inflammable gas which may be
present. The other electrode is set in the center
of the insulating cover of the safety spark gap
housing and is connected with the slip ring brush
by a short spring.

The breaker housing in which are carried the
breaker cams is so arranged that it may be rotated
through 35 degrees with respect to the armature
shaft. The movement of this housing in tjio same
direction that the armature rotates retards the igni-
tion, while moving it in the direction opposite to
rotation advances the spark timing. The direction
of armature rotation is indicated by an arrow on the
oil well cover at the driving end of the magneto.

In this type of magneto a high tension current is
generated each time the primary circuit is interrupted
by the opening of the breaker contact points and it-
is evident that ignition may be prevented or cut off
by diverting the primary current to a path which
is not affected by the action of the breaker. This
is accomplished when it is desired to stop the engine
by sending the primary current directly to the ground

HIGH TENSION MAGNETOS

327

rather than through the breaker, this being accom-
plished as described below.

An insulated grounding terminal is provided on
the cover of the magneto breaker and the inner end
of this terminal, consisting of a spring with a carbon
contact brush, presses against the breaker fastening
screw, to which, it will be recalled, the primary wind-
ing of the armature connects. The outer end of this
terminal is connected through a low tension wire
to one side of a double throw switch. The other side
of this switch is grounded by connecting it with

Of/^

Figure 145. — Grounding" Switch for High Tension Magneto.

any metal part of the engine or chassis. With this
switch open it is in the '*0N'' position and the
primary current follows its normal path across the
breaker contacts and is broken at each separation
of these contacts. When the switch is closed, or
placed in the '*OFF" position, the primary current
passes from the head of the breaker fastening screw
to the carbon brush of the grounding terminal in
the cover, thence to the switch and back to the ground.
As the primary current remains uninterrupted when

328 AUTOMOBILE IGNITION

following this latter path no high tension current,
and no spark, is produced. The switch connection
is shown in Figure 145.

Timing. — Magnetos of this type used with engines
having four or more cylinders produce two sparks
for each full revolution of the armature shaft, this
being a characteristic common to all similar shuttle
armature machines. In order to produce the neces-
sary number of sparks for each complete cycle of
each of the cylinders it follows that the armatures
of these magnetos must be driven at crank shaft
speed for four cylinder engines, at one and one-half
times crank shaft speed for six cylinder engines and
at twice crank shaft speed for eight cylinder engines.

When ready for timing the engine should be slowly
cranked until the piston of number one cylinder is
at top dead center following the compression stroke.
With the magneto in place on its support the ad-
vance and retard arm on the breaker housing should
be fully retarded, that is, moved to the limit of its
travel in the same direction that the armature rotates.
The magneto distributor plate should be removed by
withdrawing the two screws or by pressing in on
the two catch springs, as the case may be, thus ex-
posing the distributor gear and brush. The cover
of the breaker should also be removed. The mag-
neto armature should then be rotated by means of
the exposed distributor gear and in the direction it
is driven by the engine until the breaker contacts
are just about to separate, which occurs when the
end of the breaker arm begins to bear against one
of the steel cam segments. With the armature, break-
er, advance lever and piston in the positions described
the driving coupling should be secured between en-

HIGH TENSION MAGNETOS 329

gine and magneto. While the foregoing described
method will establish a working relationship between
magneto and engine which will generally prove satis-
factory, the best possible timing for any given engine
may best be found by trial. In case specific instruc-
tions for timing are given* by the car manufacturer
they should always be followed in preference to those
here given.

ZR TYPE BOSCH MAGNETOS

These magnetos differ from the DU types chiefly
in being fully enclosed and water and dust tight
in their housings. Among the minor improvements
on the ZR magnetos is that by means of which the
advance and retard lever on the breaker housing
may be placed in any desired angular position and
held in place by means of a screw ring.

Timing. — The method of setting or timing the ZR
magnetos is peculiar to these instruments, not in the
result obtained, but in the method employed, and
will therefore be described. Timing is accomplished
by observing the position of the distributor gear
through the opening exposed by lighting the oil well
cover which is on top of the instrument and just back
of the distributor, also by observing a figure **1''
through a small window in the distributor cover.

The first step in timing is to bring the piston of
number one cylinder to top dead center following
the compression stroke, then turning the flywheel
backward until the piston has moved downward from
^A to y2 inch, or, until the crank shaft and flywheel
have been turned backward from 22° to 34°. The
magneto armature should then be turned until the
figure *'l" appears through the window in the dis-

330 AUTOMOBILE IGNITION

tributor plate. Now lift the oil well cover and observe
the distributor gear through the round sight hole.
The armature is then to be further turned until the
marked distributor tooth registers with the marks
on the side of the opening. With the armature and
piston in these positions the drive should be con-
nected, care being used that the relative positions
are not disturbed. As with the DU instruments, the
exact timing for best operation may be determined
by experiment or by instructions from the manufac-
turers of the car, but in the majority of cases the
limits given will produce satisfactory results.

BOSCH DUAL MAGNETOS

While the independent high tension magneto pro-
duces an entirely satisfactory spark, it generates a
current only after the armature is in fairly rapid
motion produced by cranking. The dual sysrtem
provides the engine with an ignition system having
a battery as the source of current in addition to the
magneto and with the battery in use the engine may
be started at low cranking speeds or, with some modi-
fications, by throwing the switch or pressing a button.
In the dual system both the battery and magneto
make use of the same spark plugs, the same spark
plug wires and the same distributor, but otherwise
the two systems are distinct. The appearance of a
dual breaker is shown in Figure 146.

The Bosch dual magneto is of the standard Bosch

high tension type, timed by the revolving breaker

as in other instruments. The parts of the breaker

are carried on a base plate attached to the end of

the armature shaft and rotating with this shaft. The

HIGH TENSION MIGNETOS 331

■ segments or rollers that serve as cams are carried
. by the breaker housing as in other type*.

In addition to the parts mentioned, which are also
found on the independent machines, the dual mag-
neto is provided with a steel cam having two \obe»
or projections, this cam being built into the breaker
base. This cam acts on a lever arm which is sup-
ported by the breaker housing, this arm being so
connected in the battery cirerat that it serves a»

the arm of a breaker which interrupts the battery
current through a separate coil.

It is obvious that the high tension current from
the battery and from the high tftn&\cm. ■ma:?5wdW' ■*^'«**^

S32 AUTOMOBILE IGNITION

not be led to the spark plugs at the same time and a
further change from the independent magneto is
found in the absence of the connecting bar between
the slip ring brush and the distributor. In place,
the brush is connected to the switch in the coil hous-
ing and another wire carries the high tension cur-
rent back from the switch to a central terminal on
the distributor.

When running on the magneto, the high tension
current that is produced flows to the distributor by
way of the switch contacts. When running on the
battery, the primary circuit of the magneto is
grounded through the switch and there is therefore
no production of high tension current by the mag-
neto armature. The high tension current from the
battery and coil then flows to the central terminal
of the distributor.

CoU and Switch. — The coil is carried within a cyl-
indrical housing on the front of which is the switch
handle and lock and on the engine end the terminals
for the magneto and battery connections. In operat-
ing the switch the entire coil is rotated within the
housing. The inner side of the stationary switch
plate is provided with spring contacts that register
with contact plates attached to the end of the coil
through which the various connections are obtained.

In order to render starting easier and to make it
possible to start on the spark a vibrator is carried
at the switch handle end of the coil and is cut into the
coil circuit by pressing the button that is seen in
the center of the switch plate. Normally this vibrator
is out of circuit, but pressing the button closes the
contacts and a stream of sparks is produced. The
vibrator is kept in action by turning the button to-

HIGH TENSION MAGNETOS

Ftsure 14T.^WirlnK of l>iial High Tension Magneto. Topt

Open Frame Machine. Bottom: Enclosed Instrument

(Boscb).

334 AUTOMOBILE IGNITION

ward the right so that the arrow points to the word

^* START."

Wiring. — The wiring diagram for the Bosch dual
system is shown in Figure 147. Terminal number 6
is used to ground the primary from the magneto
armature when the ignition is turned off or while
the battery is in use and this ground connection is
also used for one end of the secondary winding in
the coil, the other end of the secondary being con-
nected with terminal 4. The wire from number 5
terminal leads to the negative side of the battery and
inside the coil this terminal connects with one end of
the primary winding. The other end of the primary
Trinding connects with terminal number 1 from which
a wire leads to the magneto battery breaker through
which the 'battery current is interrupted after passing
through the coil. Terminal number 2 carries one end
of a wire whose other end attaches to the grounding
terminal on the magneto breaker housing and it is
through this line that the magneto armature primary
•current passes to the switch and thence to the ground
from terminal 6 when it desired to prevent produc-
tion of high tension current by the magneto. Ter-
minal number 3 carries the lead from the slip ring
or collector brush of the magneto and it is through
this wire that the high tension current comes to
the switch ; from the switch passing to terminal num-
ber 4 and from there to the central contact in the
distributor.

The scheme of connections through the coil for
both magneto and battery ignition is shown in Fig-
ure 148. In the magneto position at the left the
primary current from the armature is not grounded
snd the secondary current geiieTaieflL m ^iX^fc Tfta.^cL^\a

HIGH TENSION MAGNETOS

335

enters the switch through terminal 3 and passes by
way of 4 to the distributor. In the battery position
at the right the magneto primary is grounded through
'terminals 2 and 6, the battery current enters the coil
primary through terminal 5, passing to the breaker
by way of 1, and the high tension current from the
coil passes to the distributor through terminal 4.

TIMING BOSCH D AND DR MAGNETOS

A majority of the Bosch magnetos of the' inde-
pendent DU type and of the Dual type are of the

secojfo/iifY^

D/srmuro^

O/STM/Sl/roA

/f/t/i/lTifU
PBIMM/IY

iflTTiAY

BffTT£/fy
/l/i££r/y£

Figure 148. — Schematic Diagram of Coil and Switch Circuits
for Dual Magneto. Left: Magneto Ignition.
Right: Battery Ignition. (Bosch.)

construction designated as Model 5. These magnetos
differing from the D and DR magnetos, also from
the DU Model 4 magnetos, which have symmetrical
pole pieces, in that the Model 5 instruments have one
side of each pole piece extended a short ways around
the armature. The setting of the Model 5 instru-
ments is the same as given "unAet ^Otv^ ^^'s^w^'vx's^ ^cJL

336

AUTOMOBILE IGNITION

the DU machines, while the setting of the older types
will now be explained.

The magneto should be placed on its support and
secured in place, the driving coupling, however, being
left free from the shaft. The dust cover, which is
the aluminum plate under the arch of the magnets,
should be removed. In some designs the dust cover
is secured in place with screws while in others it is
held by spring catches. Removal should be done with
care to avoid injuring the windings on the armature.
The engine should then be slowly cranked until the
piston of number one cylinder is at top dead center
following the compression stroke. With the engine
in this position the armature of the magneto should
be revolved until it is approximately in the position
shown in Figure 133. The exact setting of the arma-
ture is determined by the dimension marked **e" as
follows :

Magneto type D4

4 cylinder

14 to 17 millimeters

6 cylinder

18 to 22

'' DR4

4 cylinder

14 to 17

'* DR6

6 cylinder

18 to 22 '*

'' DBS

8 cylinder

16 to 22 "

<< DU4

4 cylinder

13 to 15 ''

'* DU6

6 cylinder

16 to 20 *'

With the armature held in proper position accord-
ing to the distances given above and for the rotation
shown in the illustration as observed from the driving
end of the machine, the gear or coupling should be
secured. This setting places the armature and en-
gine crank shaft in such a relation to each other that
the current produced by the magneto is at its maxi-
mum when the piston is in the firing position.

HIGH TENSION MAGNETOS

337

NU TYPE BOSCH MAGNETOS

The NU magneto differs from practically all other
instruments of Bosch or other makes in doing away
with the usual type of distributor and replacing it
with two collector or slip rings in a manner that
will be explained. This magneto is suitable only
for comparatively small engines having four cylindera
and of the four cycle type.

SP/i/fic pii/QS

VSAAAAAA/WT""

Figure 149. — Schematic Diagram of Circuits of High Tension
With Double Ring Type of Distributor (Bosch,

.Model "NU").

•

This magneto is of the true high tension type with
its armature winding composed of two sections; one,
the primary, consisting of a few turns of heavy wire
and the other, a secondary winding, consisting of
many turns of fine wire. The action of the magneto
in generating current by rotation of the armatxjx^
between the poles of permaneivt ia«L^wi\s», ^^Vt^^^^ss^

338 AUTOMOBILE IGNITION

and the general construction of the armature is the
same as in other types of Bosch magnetos.

The principle of operation and the electrical cir-
cuits of the NU magneto are shown in Figure 149
which is a schematic diagram only and does not show
the relative positions of the parts as they are in the
machine. The construction of the driying end of
the armature on which are carried the two collector
rings with their four brushes is shown in Figure 150.
In the magneto the two rings are side by side at the
€nd of the armature and four brushes, two carried
in each holder bear against the two rings. In the
schematic diagram, for the sake of clearness in ex-
plantation, the rings are separated to show the con-
nection of the armature winding.

The beginning of' the primary armature winding
is in metallic contact with the armature core. The
other end passes to the breaker through the fastening
screw and thence to the ground again as in the DU
instruments already described.

In the NU magneto, unlike most other machines,
the secondary winding is completely insulated from
the primary and from any ground connection within
the magneto. The two ends of the secondary wind-
ing are connected to two metal segments, one segment
iiveach of the collector rings. The segments are set
diametrically opposite each other around the arma-
ture shaft and are insulated from each other as well
as from the armature core and magneto frame. The
four collector brushes are supported by two double
brush holders, one on each side of the driving shaft
end plate, each holder carrying two brushes so ar-
ranged that each brush bears against a collector ring.
Upon rotation of the armature shaft, the metal seg-

HIGH TENSION MAGNETOS 339

ment of one ring makes contact with a brush on one
aide of the magneto at the same instant that the
metal segment in the other ring comes in contact with
a brush on the opposite side of the magneto. The
brushes are marked "1" and "2,'-' both number 1
brushes receiving current at the same time, and both

(Boach, Model "

number 2 brushes receiving current together one-half
revolution later.

It will be seen that two of the four brushes receive
current simultaneously and each is connected by its
wire with the spark plug in one of the cylinders.
The'seeondary circuit therefore always contains. tw<N
spark plugs and a spark wiW 'paaa Va. ^"^^^ (s^XywSs;".

340

AUTOMOBILE IGNITION

at the same instant. The connections between the
magneto and the plugs are shown in the wiring dia-
gram, Figure 151, and it will be seen that cylinders
one and four are connected with the number 1
brushes, so that these two cylinders receive their
current together ; while cylinders two and three, bein^
connected with the number 2 brushes, will receive a
spark at the same time. In a four cylinder engine
the pistons in cylinders one and four travel together
in their up and down motion, also the pistons in

Figure 151. — Wiring* of Magneto with Double Ring Type of
Distributor (Bosch, Model "NU").

cylinders two and three travel together.

With the piston of number one cylinder at top
center following the compression stroke a spark will
pass at its plug. At the same instant a spark will
pass at the plug in number four cylinder, whose
piston is also at top dead center, but following the
exhaust stroke and with the combustion space filled
with dead gas. Consequently there is no ignition
in cylinder four although ignition does taKe place in
number one which is filled with, iredi compressed

HIGH TENSION MAGNETOS 341

mixture. A similar condition exists between cylinders
two and three so that but one ignition takes place,
although two sparks pass.

Some care should be exercised in the setting and
timing of the NU instruments to avoid having the
spark take place too late. It will be realized, that
with an extremely late timing, the spark taking place
in the dead cylinder might come after the piston had
started down on the inlet stroke which follows the
exhaust. Should the inlet valve in that cylinder have
opened before the spark passes, the fresh incoming
mixture might become ignited, thus causing a back
fire. While this is a remote possibility, it should be
considered in the timing operation.

The secondary circiiit with the segments in con-'
tact with the brushes numbered "1" starts in the
secondary winding, passes through one brush to a
spark plug, through the ground or metal of the
engine to the shell of the spark plug in the cylinder
connected with the other brush numbered ''1" and
through this second plug back to the other brush.
From this brush the current passes to the ring seg-
ment and returns to the armature v/iriding. The
timing and care of this magneto is similar in prac-
tically all respects to that of the DU instruments
which 'have been described.

EISEMANN G4 MAGNETOS

In common with all Eisemann magnetos made
during recent years the 64 types are of the true high
tension variety having both high and low tension
windings on the armature and generating the sec-
ondary current ready for the spaxk V^^ -^^S^c^sss^

342 AUTOMOBILE IGNITION

additional outside parts. The first G4: instruments
are designated as Edition One and a later model is
Edition Two, these being generally written, I Edit
and II Edit respectively. The difference between the
two magnetos is found in the breaker, the pole pieces
and in the frame and housing construction.

Breaker Edition One, — This breaker design is
shown at the top of Figure 152. The cam is sta-
tionary except for the slight movement required in
advance and retard, while the breaker arm and con-
tact carrying parts are mounted on the end of the
armature shaft and revolve around the cam. On
the revolving breaker base are carried two members
with the two contact points. The fixed contact is
mounted on the end of an adjusting screw and sup-
ported on a block which is insulated from the base
proper by a fibre washer. Current from the arma-
ture low tension winding comes to this insulated
block and fixed contact through a long screw which
fastens the breaker to the armature shaft. The mov-
able contact point is carried at the end of a flat spring
called the contact spring and the other end of this
spring is screwed to a hollow post inside of which
is a carbon brush which maintains a sliding contact
with the frame of the magneto and serves to ground
the breaker base and the movable contact. Back
of the contact spring, and separated from it af the
contact end by a fibre block, is the pressure spring
which serves to close the contacts when not acted
upon by the cam. All of the parts described in this
paragraph revolve with the armature.

Over the breaker end of the magneto fits the cover
of which the advance and retard levers are a part.
Except for a movement of thirty degrees for advance

HIGH TENSION MAGNETOS

Figure 152.— Breakers of HiKh
Carried at Center - - -
In Rim ot He

slon Magneto. Top : Cama
Bottom : Cams Carried
Elaemann, '■04" Models.)

344 AUTOMOBILE IGNITION

and retard, this cover is stationary and at its center
are carried the parts of the cam shown in Figure 152
as attached to the breaker cover body. These parts
include two fibre bumpers directly opposite one an-
other and an oil wick at the top. As the breaker base
revolves, the contact spring comes in contact with
these fibre bumpers and as the spring rides over the
"bumper the contacts are separated in the position
shown in the illustration. Once during each revolu-
tion of the breaker the contact spring passes the oil
wick and receives a film of lubricant. The partial
rotation given the breaker cover by the advance lever
•changes the position of the fibre bumpers and acts
to open the contacts earlier or later in the revolution.

In the outer end of the long screw which holds the
iDreaker base to the armature shaft is a wire gauze
l)rush and while the cap is over the breaker cover this
l3rush bears against a metal block to which the wire
from the magneto switch attaches. With the switch
dosed so that it establishes a connection with the
metal of the car, the low tension current from the
armature is grounded through the wire gauze brush
and the wire to the switch.

Breaker, Edition Two, — The breaker mechanism of
this model is similar in many respects to those designs
found on a number of other high tension magnetos
and might be taken as typical of true high tension
magnetos. It is also like the breaker used with older
models of Eisemann magnetos such as the EU, ED,
E]\I and others.

The design is shown below in Figure 152. The re-
volving parts which carry the contact points are
-carried by the base plate which is attached to the
-end of the armature shaft by a long screw with a

HIGH TENSION MAGNETOS 345

tapering head and held in place by means of a key
and keyway. On this revolving base, but insulated
from it hy a fibre washer is a block through which
passes the adjusting screw carrying one of the con-
tact points. The other contact point is carried on,
one end of a rocker arm which is supported by a
pivot bearing with a fibre bushing. The pivot ig
covered by one end of a flat spring and the tension
of this spring serves to hold the rocker arm on the
bearing. The other end of this rocker arm carries*
a fibre bumper which rides over the cams and forces;
the contacts apart by moving the arm on the pivot.
Fastened to the bumper end of .the rocker arm is
one end of a flat spring. This spring is placed under
tension by attaching the other end to a small brass,
post and the bending of the spring holds the contact
points closed except while they are separated by
the cams.

Inside of the breaker housing are carried two steel
cams set diametrically opposite each other and over
which the fibre bumper of the rocker arm passes dur-
ing the revolution of the armature and breaker base.
During this passage" the arm moves, separating the
contacts, and the spark takes place. Just before the
fibre bumper comes in contact with the surface of
the cam it wipes past an oil wick carried in the cam
and thereby collects a small quantity of lubricant.
The breaker housing with the cams may be turned
through thirty degrees around the center by means
of the advance lever attached to the housing. Thiff
partial revolution serves to control the amount of
spark advance inasmuch as the changing position of
the cams will cause the contacts to open earlier or
later according to the direetioxi ol TaoN^Asxet^,.

346 AUTOMOBILE IGNITION

Armature. — The armature ia of the conventional H
slot type and is shown, in Figure 153. In the slot is
carried the double armature winding and at the drive
end of the slot is placed the condenser. The armature
end plate at the drive end carries a brass slip ring
against which bears the carbon grounding brush, this
brush being supported by a screw set into the base
of the magneto. Through this brush are grounded
the primary winding, the secondary winding and the ,
condenser.

of High Tension Magneto

At the breaker end of the armature is the pinion
which drives the distributor gear and separated from
this pinion by a series of insulating corrugations is
the high tension collector ring to which one end of
the high tension winding of the armature attaches.
Bearing against this ring is the collector brush which
carries the high tension current to the center of the
distributor cap.

Distributor. — The Eisemann distributor as shown
in Figure 131 is of the wipe contact type having a
metal segment set into the rotor -which is carried l»y

HIQH TENSION UAQNEXOS

" at Top and Model "Bi&" bX '&oU/itci

348 AUTOMOBILE IGNITION

the distributor gear. This segment revolves past a
series of carbon brushes, one for each cylinder of the
engine, which are mounted in the distributor cap.
In the center of tl^e distributor cap is another brush
which bears against the inner end of the revolving
segment and this brush is connected through the bod/
of the distributor cap with the collector brush which
takes the high tension current from the collector
ring on the end of the armature.

A safety spark gap is provided by means of one
or two small brass screws which pass through the
armature housing and have their inner ends extend-
ing to within about % of an inch of the collector
ring carried by one end of the armature shaft.

Diud System. — This type of Eisemann magneto is
also built as a dual instrument by modifying the
breaker and distributor to allow separation of the
battery current from that generated by the magneto
armature. Wiring for Eisemann dual magnetos is
shown in Figure 154.

The breaker housing has two compartments, one
being of the type already described for single mag-
neto ignition and the other carried outside of the
first one and containing another complete breaker
mechanism through which the battery current passes.
This breaker arm is so placed in relation to the
actuating cams that the opening of the contacts oc-
curs 10 degrees later in the revolution of the arma-
ture than does the opening of the magneto contacts.
The advance and retard is the same as for the mag-
neto side, being operated from the same timing arm.
This dual breaker is somewhat similar to the one al-
ready described as on Bosch magnetos.

The distributor for the dual instrument is similar

HIGH TENSION MAQNBTOS 349

to those used with the single ignition types except
that there is no direct connection through the cover
from the lower carbon brush which touches the col-
lector ring and the center brush which touches the
distributor rotor. Instead, the collector ring brush is

connected with one of the terminals and from thia
terminal the high tension magneto current may be
led through the switch and back to the center brush
with magneto ignition in use, or, the high tension
battery current may be led from. iVa «i,a^ V^ '>i«.

350 AUTOMOBILE IGNITION

center brush of the distributor with the battery igni-
tion in use. With a four cylinder magneto there
are then six terminals on the distributor; four being
for the spark plug wires, one for the collector ring
brush and one for the center distributor brush. In
all other respects the dual instrument is the same
as the single ignition type.

The coil unit used with dual magnetos contains,
in addition to the coil itself, a device for starting
the engine by manual production of a spark and
the ignition switch. The sparking mechanism is
illustrated in Figure 155 and consists of a ratchet
having three teeth which engage with a roller A on
a lever B. This lever is mounted at one end on a
hinge, while at its other end is a platinum contact
extending through it to provide a contact on both
sides of the lever. The lever is operated by twisting
back and forth a starting handle which appears on
the ignition switch cover. The lever B then makes
and breaks the primary current from the battery by
making contact alternately with the fixed contacts
C and D. This results in a shower of sparks occur-
ing at the spark plug in the cylinder which is ready
for firing and if there is a combustible mixture in
the cylinder the engine will start.

Another type of coil is made which does not in-
clude the mechanical breaker just described, fbut
which, in place, is fitted with a push button which
gives but one spark in place of the series of sparks.
This type is generally used on cars fitted with engine
starters, and is similar to the device in Bosch coils
which is illustrated in the center of Figure 100.

Timing. — Setting of the magneto is accomplished
with the help of two marks which appear near the

HIGH TENSION MAGNETOS 351

circumference of the rotating member of the dis-
tributor and which are marked respectively '*L'' and
**R.'' Passing through the top of the distributor
housing is a pointed screw whose inner end acts as
an indicator with which either one or the other of
the marks just mentioned may be registered.

With variable ignition the engine should be
cranked until the piston in number one cylinder i»
at upper dead center following the compression stroke
(the firing point). The distributor cover should then
be removed and the armature shaft turned until, if
the magneto rotates clockwise when viewed from the
drive end, the mark **R'' registers with the setting
screw; or, if the rotation is anti-clockwise, until the
mark **L" registers. With the parts in this position
the breaker contacts are just opening and the dis-
tributor rotor is making contact with the brush whose
wire leads to the spark plug in number one cylinder.
With this relation maintained and with the advance
and retard lever fully retarded, the armature shaft
coupling should be fixed to the magneto drivings
shaft on the engine.

With fixed ignition the time at which the breaker
contacts open with relation to the travel of the piston
will vary according to the engine. Small high speed
engines generally require more advance than those
having comparatively large cylinder sizes. One or
more trials, with intervening operation on the road,
will serve to determine the best setting, or the ad-
vance may be learned from the carmaker's instruction
book. As a general rule the opening of the breaker
contacts should occur from 15 to 25 degrees, measured
on the rim of the fiywheel, before the piston reaches
top center following the compressioiv sttofefc.

352 AUTOMOBILE IGNITION

BISEMANN ED TYPE HAONETOS

The EU magnetos are of the true liigh tension
type having the generally adopted fonn of shuttle
armature and a typical magneto breaker attached
! end of the shaft. It is this form of mstm-

ment that has in many cases been equipped with the
Eisemann automatic advance which is illustrated in
Figure 59.

The pole pieces are shown in Pigare 126 and are
of a shape peculiar to these models. The following
description is taken from the literature of the Else- -

HIGH TENSION MAGNETOS 353

mann Magneto Company. The most extended por-
tion of the pole pieces (near the center of their
length) is approximately opposite the theoretical axis
of the winding on the armature core. This construc-
tion results in ,the flow of the magnetic lines of force
being drawn from the extremities of the pole pieces
toward the center of the core; the entire volume of
the magnetic lines of force being thus forced through
the winding. Because of the extended pole pieces
it is possible to increase the range of advance and
retard of the spark and to generate a sparking cur-
rent at low speeds. By referring to the illustration
it will be noted that at no time is the core of the
armature completely isolated from the pole pieces
and the armature, therefore, acts as a keeper and
aids in preventing demagnetization of the magnets.

Dual Ignition Type. — Instruments of the EU type
which are constructed for dual ignition are provided
with the usual form of magneto current breaker on
the armature shaft and in addition, a battery breaker
of distinctive construction on a rearward extension
of the distributor shaft. This battery breaker is
shown in Figure 156. The cam which actuates the
battery breaker runs at half the speed of the arma-
ture shaft and therefore has four lobes in place of
the usual two. The coil, switch and automatic start-
ing device are similar in all respects to those used
with the G4 instruments and which have already been
described.

Timing, — On the EU magnetos which are equipped
with automatic spark advance, the setting in rela-
tion to the engine is accomplished by means of a
specially designed arrangement of a slot and lock-
ing key which is shown in Figure 157, To xevakfc ^^v^

364

AUTOMOBILB! IGNITION

Betting the piston of number one cylinder should be
brought to top center following the eompre8S|ion
stroke; or, if a greater degree of retard is desired
for starting the engine the piston may be placed the
desired number of degrees or distance beyond top
(ienter and with the piston starting down on its firing

Figui

of I

King Key

stroke. The magneto shaft should then be turned
to the position shown in the illustration and the key
inserted as shown. In order to make sure that the
magneto is in the retard position care should be taken,
that the pin of the key catches in. one of the holes
of the rectangle. With the parts in. these positions
the magneto shaft should he coupled to the engine
drive shaft and the key then pulled oat before crank-
ing or starting the engine.

CHAPTER XII

TRANSFORMER COIL MAGNETOS

The transformer coil type of magneto ignition pro^
vides two distinct sources of current, one the mag-
neto armature and the other the battery, but all the
remaining parts of the system, including breaker,
distributor, coil, plugs and secondary wiring are the
same for either the battery or magneto. The mag-
neto armature carries a single winding which gen-
erates a low tension current and this current is car-
ried to a transformer, or induction coil located at
some point on the car outside of the magneto. From
the high tension winding of the coil the secondary
current is carried to the distributor on the magneto
and from thence passes to the spark plugs. With
the battery in use, its low voltage current is led to
the primary winding of the same coil and the high
tension circuits are the same as for magneto ignition.
The breaker mechanism is included in the primary
circuit with either source of current. A more de-
tailed description of the principles of the transformer
coil system m comparison with the high tension and
dual types has been given in Chapter Nine.

RBMY TRANSFORMER COnj MAGNETOS

While the earlier models of Remy instruments
were of the inductor type, all of the later machix^fts*

355

356 AUTOMOBILE IGNITION

have been built on the transformer coil principle.
The inductor models are described in the chapter
following. All of the circuits, both internal and ex-
ternal, of the transformer coil t3q)es are shown in
Figure 114. The coil carries six terminals, two of
which are attached to the battery, one to the mag-
neto distributor and the remaining three to the mag-
neto armature, breaker and ground connection. The
green wire from the magneto carries the low tension
armature current to the switch and the primary wind-
ing of the coil. The yellow wire provides a connection
from the primary winding of the coil to the breaker
carried on the magneto. The red wire- serves to
ground the primary and secondary winding of the
coil. This wiring is typical of all similar Remy
magnetos, and is shown in Figure 158 for both single
and two spark instruments.

Construction. — These machines are made for either
single or two point ignition, the two point types dif-
fering from their single point counterparts only in
having two distributors, one on each end of the mag-
neto, from which wires are run to the two sets of
spark plugs required by this form of ignition. The
magnetos are designed to be water and dust proof
by having the end plates machined to fit the magnets
and the distributor cover machined to fit the gear
case. Packing is then used in the joints.

The armature is of the '*H slot" or shuttle type
carrying a single low tension winding. At the drive
end of the armature is a collector ring on which
rides a carbon brush through which, together with
the green wire, the armature current is delivered
to the primary winding of the coil.

The breaker consists of a cam mounted on and

TRAI«TSFORMER MAGNETOS

357

revolving with the armature drive shaft, and oper-
ated by the cam, a breaker arm hinged aj one end,
having a fibre bumper for the cam near its center
and carrying the contact points at the free end. The

6RCCN

RCO

VCLLOW

B4TTERICS

TffilU

t'igiire 158. — Wiring of Remy Transformer Coil Magnetos.
Top: Models "P" and "32." Bottom: Two Spark

Models "30" and "31."

advance and retard lever may be located on either
side of the machine as the breaker and housing are
reversible. The timing range is about 35 degrees.

The condenser is flat and imbedded in insvila.t\\s.^
compound. The condenser "howsviv^ V\\\v \\s» ^'^'^«t

358 AUTOMOBILE IGNITION

forms a cover for the armature and is carried under-
neath the arch of the magnets and resting on the pole
pieceSo

The distributor is of the wipe contact type having
a carbon brush carried on the large distributor gear
and making contact with the center segment in the
distributor cover and with the segments in the cover
from whose terminals wires lead to the spark plugs.

The coil and switch are combined in one unit with
only the switch appearing in the driver's compart-
ment. The coil used with two point ignition mag-
netos differs from the single point type in having
two high tension terminals, one from each end of
the secondary winding. One terminal is connected
with the distributor at one end of the magneto while,
the other terminal serves the second distributor. The
two point coil is also fitted with an additional switch
by means of which one set of plugs may be cut out
and the complete high tension circuit completed
through the remaining set and the coil winding which
is then grounded at one end.

Timing. — For convenience in setting the magneto
the distributor gear is provided with a depression
near its circumference and mounted in the distributor
cover near the top is a button ^whose inner end, when
pressed by the operator, will drop into the depres-
sion in the gear. "With the button holding the gear
by means of the depression, the breaker contacts are
just about to separate and cause a spark and the
distributor is in position to deliver the high tension
current to the plug in number one cylinder. Timing
is accomplished by bringing the piston of number
one cylinder to top center following the compression
stroke and Jeaving it there. The timing button is

TRANSFORMER MAGNETOS 359

then pressed and the armature shaft turned until
the button is felt to drop into the gear depression.
The coupling between armature shaft and engine
drive shaft is then secured. If the magneto shaft
revolves clockwise, viewed from the drive end, the
distributor terminal for number one cylinder is at
the lower left hand cgmer of the distributor, while
if driven anti-clockwise the terminal for number one
is at the lower right hand comer with the setting
made as described.

SPLITDORP TRANSFOEMEB COHj MAGNETTOS

The principles of operation of the Splitdorf in-
struments are the same as for the other types of
transformer coil magnetos, the differences being
found in details of construction. The armature is
of the usual ''H" or shuttle type carrying a single
low tension winding one end of which is grounded
through a carbon brush passing up through the base
plate of the machine and bearing against a ring
mounted at the drive end of the armature. The
other end of the primary winding is connected with
a long screw which passes through the center of /the
breaker and against the end of which rests a collector
brush mounted in the breaker cover. This collector
brush it attached to the terminal on the breaker cover
and from this terminal a line leads to the low tension
winding of the separate coil. This' is the terminal
which, in the wiring diagrams is marked **A.'*

The breaker cam with its two lobes is carried by
one end of the armature shaft and it actuates a
breaker arm which is hinged at one end, has the
contacts at the other end and ^^\v\c?a. e,^TTv^ ^^ ^Ssstfe

360 AUTOMOBILE IGNITION

roller at its center, the cam lobes operating against
this roller. This breaker is so designed that by a
change of the cam and of the meshing of the distribu-
tor gears it may be used for either direction of
rotation. The method of making the change may
be understood by reference to Figure 134. The
breaker box should be removed, the driven end of
the armature shaft held firmly with a pair of pliers
and the small nut securing the cam removed. The
cam is held with a Woodruff key and may be pulled
or pried off. Turn the cam over and replace it the
opposite way, then secure it with the nut. Next
remove the distributor and the insulated brush that
is located at the driving end of the back plate of
the magneto; take out the four screws that hold
the plate, remove the plate and slide the armature
back, bringing the distributor and armature shaft
gears out of mesh. Then set the armature back with
the gears meshed so that the distributor is in cor*
rect relation to the carbon brush and the cam just
ready to open the contacts. For right hand rota-
tion, looking from the driven end, the relation of the
parts should be as shown in the right hand illustra-
tion of Figure 134, while for left hand rotation the
relation should be as in the left hand illustration.
This illustration also shows the position assumed by
the armature core with reference to the pole pieces.
The distributor is of a wipe contact type having
a rotating member fixed on the large gear and carry-
ing a T shaped segment, the inner end of which re-
ceives the high tension current from a carbon brush
whose terminal leads to the coil and whose outer end
delivers this current successively to the several car-
bon brushes which are connected with the spark

TRANSFORMER MAGNETOS

Bottom : Models "A,"

Dftsh Switch and CoW.

362 AUTOMOBILE IGNITION v

plugs. All of these brushes are set into the dis-
tributor cover.

The coil may be separate and mounted at any con-
venient place, or it may be in a unit with the switch.
In either case a safety spark gap is carried on the
coil housing. All of these coils provide separate
terminals for both positive and negative sides of the
battery and under no circumstances should either
pole of the battery be grounded. Typical Splitdorf
wiring diagrams are shown in Figure 159.

Timing is done in the usual manner; that is, by
bringing the piston of number one cylinder to top
center following the compression stroke, turning the
armature shaft in its direction of rotation, until the
breaker cam is about to separate the contacts, and
with the timing lever fully retarded, making the driv-
ing connection secure.

In starting the engine on the battery ignition the
spark lever should, as in all other similar cases, be
fully retarded to avoid dangerous back firing. How-
ever, with these types of magnetos in good order,
starting may be easily accomplished from the mag-
neto alone by advancing the timing lever from one-
half to two-thirds of its travel and cranking smartly
for a half or a full turn.

CHAPTER XIII

INDUCTOR MAGNETOS

In all of the types of magnetos so far described
the coils of wire in which the current is generated
by the magnetic lines of fofce have been carried by
a revolving armature in such a way that the inten-
sity and direction of the magnetic flow changes dur-
ing rotation, thus producing the electrical flow.
There is another type of instrument used in large
numbers with which the coils of wire remain sta-
tionary and with which the change in magnetic flow
is secured by means of a revolving part called an
inductor.

The action of the inductor may be explained by
reference to Figure 160. The magnets M are of
the horseshoe type and have their positive and nega-
tive poles on opposite sides of the rotating member
or inductor A which is carried on the driving shaft
S. The inductor consists of a central cylindrical
portion having extension pieces at either end, the
piece at one end pointing in one direction and that at
the other extending the opposite direction away from
the shaft. The inductor rotating member is made
from laminated iron through which the magnetic
lines of force easily flow. Wound around the center
of the cylindrical part of the inductor is the sta-
tionary coil C in which the current flow is induced.

With the magneto parts in the po^\\\«tv ^Xivg^nxn^ ^2i^»

363

8W AUTOMOBILE IGNITION

the upper right. Figure 160, the flow of magnetism
■ is from the positive to the negative magnet pole and
passes downward through the coil winding. At the
end of a quarter turn, in the lower left diagram
the inductor is in such a position that its extensions
are midway between the magnet poles and the flow

Figure ISO. — Principle of Inductor Masneto Operation.

of lines of force has stopped and is ready to re-
verse. It is at this instant that a powerful flow of
current is generated in the coil just as in the revolv-
ing armature type, the flow taking place when the
mairnetism reverses. In the lower right diagram,

INDUCTOR MAGNETOS 365

one-half revolution from the position just above,
the flow of magnetism through the center of the coil
is again taking place but now the lines of force pass
upward, or in tlje reverse direction from the first
case. Continued revolution of the driving shaft and
the inductor causes continued changes in the direc-
tion and intensity of the lines of force with resulting
impulses of current flow in the coil wiiiding.

The inductor principle of construction is the most
simple of all types, both electrically and mechani-
cally. It eliminates revolving wires, carbon and other
brush contacts, moving conductors and other ob-
jectionable items. However, it does not show the
efficiency shown by the revolving armature machine
and the high grade construction of this latter type
makes the items of apparent trouble of little im-
portance in actual practice.

REMY INDUCTOR MAGNETOS

The flrst Remy inductor magnetos to be generally .
used were of the **S" type, a few of the construc-
tional details of which will be mentioned. This ma- "
chine carried the breaker shown in Figure 161 con-
sisting of the double lobe cam on one end of the
driving shaft which operates the V shaped contact
arm. This arm is carried on a pivot at the bottom
and is actuated by the cam revolving against a small
hardened steel plate attached to the arm. The mov-
able contact is mounted at the free end of a flat
spring carried by the breaker arm, while the sta-
tionary, or adjustable, contact is mounted in the
breaker housing.

The screw canying the ^Yai^cmscrj Vt^^^^^^ ^^^sar

366 AUTOMOBILE IGNITION

tact is of hard rubber and on the outside of the
housing is fitted with a milled- rim that allows easy
turning of the screw one way or the other, thns pro-
viding an adjustment by means of which the gap
between the contacts, when separated, may be alt-
ered. The adjustment is maintained by a bronze

Elgure ISl. — Breaker Used wUh Remy^ Inductor MagnetoB,

spring having a square hole which engages a squared
portion of the adjusting screw. Pressing this spring
releases the screw. The contact carrying screw is
also used as a mounting for one of the wiring ter-
minals to which is attached the yellow wire from
the coil.
The distributor is of the jump spark type having
a brass segment attached to the rotating member and

INDUCTOR MAGNETOS

EiBure 162. — Wiring of Model "S" Remy Inductor Magneto,
Top: Internal "' '•- t^-*' ^— > ^ ->■ —

368 AUTOMOBILE IGNITION

to which the high tension current from the coil is
carried by a carbon brash mounted in the distributor
cover. The rotor segment passes within a short dis-
tance of metal pins set around the inside of the dis-
tributor housing, there being one pin for each cylin-
der to be fired. The complete circuit, both high and
low tension, for these magnetos is shown in Figure
162.

Magnetos which followed the **S" type just de-
scribed are known as models **RD'' and **RL," the
''RD '' type being shown in Figure 163. The inductors
in this machine are constructed of iron laminations
and each one is balanced by attaching on the opposite

' side of the drive shaft a weight of non-magnetic metal.
The construction of the breaker and distributor may
be clearly seen from the illustration. The breaker con-
tact gap, as in the older instruments, is provided
with an adjustment which may be altered from out-
side the housing. The cam is kept covered with a
thin film of lubricant by means of a small wick Qiler
which is shown. The distributor is of the jump spark-
type with the segments for the spark plug terminals
iiQbedded in the housing wall. In this instrument the .
central carbon brush of the distributor is mounted
in the rotating member while th6 distributor cover
carries a small metal boss connected with the ter-
minal which carries the wire from the high tension
winding of the transformer coil.

The electrical circuits for the Model **RL" mag-
neto are shown in Figure 164. Between the mag-
neto and coil are three wires, one green from the
stationary magneto winding to the primary winding
of the coil, one yellow from the magneto breaker

leading to the coil primary and starting button of

INDDCTOR MAGNETOS

370 AUTOMOBILE IGNITION

the switch and one red which serves to groand the
high tension and low tension windings of the coil.
The switch is fitted with a button which upon opera-

tion by the driver opens and closes the battery cir-
cuit through the coil primary, thna producing a
spark which passes to the plug oi tlie ayUnder ready

INDUCTOR MAGNETOS 371

to fire. It should be noted that both sides of the
battery are connected with the coil and neither side
grounded. It is not advisable to use storage bat-
teries with Remy magnetos of Models **S,'' **T/'
*'RD" or **RL/' dry cells being recommended in
all cases.

DIXIE MAGNETOS

The principle of operation may be understood by
reference to Figure 165. The magneto consists, in
its principal parts, of a set of magnets, a rotating
member, a special field structure carrying the coils,
the coil windings, a breaker and a condenser.

The rotating member, or rotor, consists of two
revolving wings N and S, shown at 1 in the illus-
tration, which are separated by a Jironze center
piece. These wings are carried by the magneto drive
shaft and revolve between the poles of the magnets,
one rotor revolving adjacent to the North pole while
the other revolves close to the South pole. Because
each rotor always revolves close to its own pole of
the magnets, they always maintain the same mag-
netic polarity, one always being positive while the
other is always negative.

Again viewing a section of the magneto and look-
ing across the magnets as in 2, 3 and 4 of Figure
165, in place of through the arch as in 1, it will
be seen that the rotor is enclosed by the lower ends
of an arched field structure, on the upper part of
which are placed the coil windings. As the rotor
revolves it causes the magnetic lines of force to be
changed about so that the magnetism flows back and
forth through the field straetvxT^ ^tA \5sNfc ^-^^^ 5^"^ ^^"^

372

AUTOMOBILE IGNITION

windings, first in one direction, then in the other,
according to the position of the rotor in relation to
the poles of the field structure.

Still referring to Figure 165 it will be seen that,
by rotating the wings very tlose to the ends of the
magnets, they are in effect the rotating poles of the

ym:

tmm

•F

PIgrure 165. — Principle of Inductor Magrneto with HotatlnflT

Magnet Poles^ (Dixie).

magnet. At right angles to the rotating pole pieces
or wings is the field structure consisting of laminated
pole pieces F and G carrying across their top the*
windings W. When N is opposite G the lines of
force flow from one pole N of the magnet to G and
through the core C to F as shown in 2 of the illus-
tration. As shown at 3, the pole N has moved over
to F and the direction in which the lines of force
flow is reversed through the core and windings, now
passing from F through C to G. At 4 in the illus-

INDUCTOR MAGNETOS

373

tration the rotating pieces occupy a podtion midway
between the two foregoing so that the field pieces P
and Q are magnetically short circuited and all the
linea of force are removed from the core C.

Figure 16S. — Internal Circuits of Inductor Ma^rneto. Top:

PrimSiry Circuit. Dottom: Primary and Secondarjr

Circuits (IMxle).

Primary and Secondary Circuits. — The primary
circuits are shown at the top of Figure 166. The
core of the coil A is stationary, being represented m.
the preceding figure by C. The inner end of the

374

AUTOMOBILE] IQNITION

primary winding P is grounded on the core. Q indi-
cates the metal frame of the machine. The condenser
R is carried just above the coil and is removable by
taking out two screws. The terminal D is a screw
on the head of the coil and the wire 7> connects
directly to the contact Y of the breaker.

The secondary circuit is also shown at the bottom of

FIgu:

Cylinder

Pignre 166. One end of the secondary" is gi^nnded
while the other is connected to the rotor of the dis-
tributor which sends the high tension current through
the spark plugs back to the ground. A safety spark
gap is provided between the framework of the machine
and the central connection for the distributor.
Breaker. — The breaker is shown in Figure 168.

INDUCTOR MAGNETOS 375

The parts of the mechanism shown in the illustration
are stationary while the magneto is running. The
adjustment between the contact points X and Y is
made by the screw which is shown. These contact
points should separate when the air gap between one
of the rotor wings and the pole piece carrying the
coil is between 15 and 35 thousandths of an inch. The
breaker is made adjustable as shown at the right in
Figure 168 so that this relation may be secured with-
out diflBculty and may be regained should the fibre
Wmper become worn. The bearing holder in which
the breaker base is fastened has slotted holes, permit-

Figure 168. — Construction and Adjustment of Dixie Magneto

Breaker.

ting the breaker base to be rotated several degrees in
either direction from its original position. As the
breaker parts are mounted on the base, the positions-
of the rotor at which the cam causes the contacts to
separate can be varied by as many degrees as the
breaker can be moved. The four screws which pass-
through the breaker base and bearing holder thread
into the clamping ring A. To adjust the breaker it
is necessary to loosen the four screws, then; if the
air gap between rotor- wing and pole piece is too
small, rotate the breaker base in the same direction
that the cam rotates while in operation. If the gap

876 AUTOMOBILE IGNITION

18 too large, rotate the breaker base in the direction
opposite to that of the cam's rotation. The screws
ehould then be securely tightened.

Advance and Retard. — It will be noted from the
foregoing explanation of the breaker base construc-
tion that this member is securely fastened to the body
of the magneto. This fastening takes place between
the breaker base and the pole piece structure on
wluch is carried the coil winding and between the

ends of which the rotor turns, therefore the relation
between the point at which the breaker contacts
separate is always the same with reference to the
relative positions of the rotor and its pole pieces, this
opening taking place at the instant of greatest cur-
rent volume in the coil and just as the magnetic flux
undergoes the greatest change.
The advance in the Dixie magneto is obtained by

INDUCTOR MAGNETOS 377

rocking the entire pole piece structure together with
the coil windings and the breaker base between the
arch of the magnets as shown in Figure 169. This
rotation of the breaker base with the contacts changea
the relation of these parts to the cam on the drive
shaft as shown in the illustration so that the time of
opening and closing the contacts may be made earlier
or later while still maintaining the same relative
positions of the rotor and pole pieces.

Timing. — ^With the piston of number one cylinder
at top center after the compression stroke the mag-
neto shaft should be turned in its direction of rota-
tion while the timing lever is at full retard. Just as
the contacts of the breaker start to separate the mag-
neto shaft should be coupled to the engine shaft.^

CHAPTER XIV

LOCATION AND REMEDY OF TROUBLES
CARE AND MAINTENANCE

Cleanliness, — Dust and dirt, when in combination
with a film of oil, form a conducting path 'through
which an escape of secondary current, or even of
the primary, may easily take place. It is therefore
important for the successful operation of ignition
apparatus that strict cleanliness should prevail at
all times. The interior of the breaker housing and
of the distributor should be kept free from dust, oil
and moisture by a frequent use of gasoline, either
applied direct or by means of a clean cloth moist-
ened slightly. The use of gasoline is preferable to
kerosene because it dries without leaving the film
that is left by kerosene. The objection to the use of
gasoline is in the danger from fire should any spark
occur. It is, therefore, extremely important, when
doing this work, that the ignition switch should be
open, or in the **Off'' position; or, better stiir, that a
wire should be removed from one terminal of the
battery and its end taped until the work is com-
pleted. If this is not done, and should the primary
<»ircuit be completed, an accidental separation of the
breaker contact points would probably cause a blaze.

Any foreign substance on the inside or outside sur-
faces of the distributor housing or of the cap might
-easUy form a conducting path between the various

378

TltOUBLES AND REMEDIES 379

brushes, pins or segments. Because of the extremely
high voltage of the secondary current it will leak
across a surface having a very thin film of dirt of
any kind and this will cause a peculiar missing and
erratic action of the engine.

Space around the terminals of all wires attached
to the coil, condenser, resistance unit, breaker, dis-
tributor and batterj^ should be kept thoroughly clean.
Special care should be given to the top of the storage
battery between the terminal post^ because a film of
the battery electrolyte may easily form at this point *
due to spilling while testing the gravity or to slight
splashing caused by the battery's passing when fully
charged.

It is advisable in all cases to provide a magneto
with a leather or oil-proof fabric cover which will
shield this instrument against oil from the engine
and from moisture and dust. Some of these covers
enclose the magneto only, while others are provided
with extensions covering the wires between the mag-
neto and the tubes through which the wires pass to
the plugs, distributor and other parts of the ignition
system.

Rubber thimbles or caps are made which enclose
the terminal connections on the distributor and
breaker and shields of various forms are made for
practically every part of the mechanism which car-
ries ignition current.

The outside surface of the spark plug insulation is
oftentimes neglected, and because of the action of the
fan in continually blowing a current of dust laden
air over the engine, the plugs will finally gather a
layer of dirt which will conduct a part or all of the
high tension current and thus e^M^^ tv. ^w^otv»5sq>s. ^js^

380 AUTOMOBILE IGNITION

intermittent missing. Porcelain or stone shields are
made in forms suitable for placing over the outside
of the plug and extending for some little distance
over the spark plug end of the wire coming from the
distributor. These shields are generally used on
motor boat engines which are exposed to the action
of the weather.

Lubrication. — Because of the fact that, in most
forms of ignition apparatus, lubrication is only called
for about once in each thousand miles of running it
is usually neglected for much longer times. Such
neglect, as it affects the breaker or distributor
mechanism, will probably cause no greater damage
than a temporary interruption of the operation of
these parts. This will bring its own remedy because,
until the remedy is applied, the engine will not run.
Neglect of bearing lubrication for any length of
time will result in ruining the bearings themselves,
and very probably in ruining other parts of the
mechanism as well, especially if ignition is provided
by a magneto. '

While some operators give too little lubrication,
others give too much by flooding the apparatus when
oiling is done, or by too frequent application. Too
much oil is one of the most common troubles of the
breaker because this oil will finally creep to the con-
tact points where it will cause severe arcing and per-
manent damage. Oil on these contacts will reduce
their useful life to one fourth of its normal length.

A wrong kind or quality of lubricant may also have

its effect on the continued operation of the ignition

system. Engine cylinder oil is not a suitable form

for these delicate parts because of its too heavy bodj^

and its tendency to thickeiv ox ^tcv ^\th cold. -A

TROUBLES AND REMEDIES 381

Hght bodied oil, such as sold for use with sewing
machines, will be satisfactory for use in all oil wells
and wick oilers and for application to breaker parts
when called for. Ball bearings, when exposed for
packing, should be filled with vaseline rather than
with any form of cup grease such as used at other
points about a car.

Many forms of breakers are designed to operate
without lubrication in the breaker proper and all
breaker oiling other than that done through oil holes
leading to the bearings should be done with care and
without any excess being applied. Oiling of pivot
bearings should be avoided when these parts are pro-
vided with fibre or other anti-friction bushings. When
required at all, but a very little oil should be applied
to the exact point of use by means of a tooth-pick or
pointed match. Some breakers are provided with a
wick through which the cam surface is kept continu-
ally covered with a thin film of oil and the action of
others may be assisted by wiping the cam surface
with a cloth moistened with light oil.

With a wipe contact distributor having its seg-
ments set in a track followed by the rotor brush, this
track should be wiped at intervals with a clean cloth
slightly moistened with gasoline. After all carbon
dust and soot have been removed, the track should
be wiped with a cloth having a very light application
of vaseline. If the segments are found to be rough-
ened or scored they may be smoothed by rubbing
with the finest grade of emery or crocus-cloth. After
this operation the track should be polished with a
leather pad before lubrication.

All magnetos, and a majority of battery breakers
and distributors, are provided with one or more oil

382 AUTOMOBILE IGNITION

holes from which ducts lead to the shaft bearings
and other parts which require lubrication. Specific
instructions are generally furnished as to the amount
of oil to be given at certain intervals, the require-
ments usually being from five to ten drops of light
machine oil every five hundred to one thousand miles
of driving, this oil being placed in each of the open-
ings. The oil holes are generally covered with a
spring-closed cap and will be found near the top of
the magnet arch, back of the distributor, at either
side of the breaker housing and at the drive end of
the armature shaft in magnetos. In battery systems
oilers are usually found at one side of the driving
shaft or at the side of the breaker housing.

Many of these oilers are provided with overflows
which carry away any excess of oil that may be
applied, provided the overflow tubes are open. Others
have no such safety arrangement and with them care
must be exercised not to flood the bearings so that
the excess of oil will find its way to current carrying
parts and contacts.

All control members, such as ball and socket joints,
slides, pin bearings, etc., should be examined and oiled
frequently so that excessive wear and resultant play
may be prevented. Any great looseness that develops
in the ignition control parts should be taken up
because correct timing of the spark may be seriously
interfered with by neglect of this precaution.

In Chapters Seven, Eight, Eleven, Twelve and
Thirteen will be found many suggestions as to the
proper care of the various makes of ignition equip-
ment and these paragraphs should be referred to for
certain detailed information and exceptions to gen-
eral rules.

TROUBLES AND REMEDIES 383

TROUBLES OTHER THAN IGNITION

The ignition system is veiy often blamed for
improper operation of the engine when the real fault
lies with some other part of the power plant. Because,
as a general rule, ignition devices and the action of
the dlectric current are not well understood, the
operator will attempt adjustments and alterations on
these parts when they are not required. Should a
preliminary^ test show that a spark is reaching the
plugs, nothing further should be done with the elec-
trical parts until consideration has been given to the
fuel system and to the valves of the engine.

In case of engine stoppage, or of a failure to start
promptly, the driver will naturally make sure that
the ignition switch is turned on and that there is a
supply of fuel in the tank. Granting that the quantity
of fuel is sufficient, it should be seen that the feeding
device, either vacuum or pressure system, is operat-
ing and sending gasoline to the feed piping. Should
it be found, by depressing the priming pin, examin-
ing the float bowl or opening a drain cock or plug,
that no liquid reaches the carburetor, the fuel lines
should be examined for clogging due to some foreign
substance or to the fact that a valve may have been
closed and not opened before the attempt to start.

Should the fuel reach the carburetor bowl, it is
possible that one or more of the adjustments for fuel
or auxiliary air may have become improperly set;
or, if this is known not to be the case, then it may be
possible that the carburetor jet is clogged with some
small impurity. Should the engine start and then
come to a gradual stop, it indicates that there is some
clogging of the fuel lines. If the engine runs with

384 AUTOMOBILE IGNITION

but little power and with a spitting or popping noise
it indicates that the carburetor mixture carries. too
much air or too little gasoline; while if the engine
operates with an intermittent miss in some cylinders
or with a galloping action, it indicates that the mix-
ture contains too much gasoline or too little air. It
is, of course, not within the province of this book to
go into the matter of carburetor adjustment.

Because of the low grade of gasoline now available
it is essential that the incoming air for the carburetor,
or the fuel itself, be heated in order to produce a sat-
isfactory mixture. Heating of the air supply is the
most generally used method and it should be seen
that the stove on the exhaust pipe and the tubing
from this stove to the air intake of the carburetor
are in place and securely fastened. Any valves
placed in this air line should also be examined to
make sure that they close for choking while starting
a cold engine and that they assume a fully opened
position with the hand control in the running position.

Valve Troubles,— The engine valves must open and
close at the proper time, they must open the correct
amount and close promptly and they must make a
reasonably gas tight joint with their seats in order
to assure correct engine operation.

The kind of engine operation that results from
leaky valves may easily be mistaken for ignition
trouble, but the valve condition may be readily ascer-
tained by cranking the engine slowly by hand. The
degree of compression, or the resistancffe to turning,
should be practically uniform for all cylinders and if
the crank can be turned more easily during any one -
period than during others, it may be assumed that
the valves of the cylinder then under compression are

TROUBLES AND REMEDIES 385

at fault. It will then be best either to open the pet
cocks or remove a spark plug from all the cylinders
except one and again crank the engine. If consid-
erable resistance is felt, the valves for this cylinder
are sufficiently tight and another cylinder should be
similarly tested. When one or more cylinders are
found with which the compression is poor, the exhaust
valves should be removed and examined. Should the
exhausts be satisfactory then the inlet valves should
be likewise inspected. Rough, pitted or sooted valve
faces ^all for grinding to restore the compression.

During the test of compression it may be advis-
able, before going on with an examination of the
valves, to examine several other points at which the
gas may escape. The threads of priming cups, spark
plugs and valve caps, also of any cylinder head plugs,
should be tested by means of an application of lubri-
cating oil which will bubble during the compression
stroke, provided a leak is present. Leaks may also
occur between the shell and the core of the spark
plug. If the valve condition is good and there are
no other outside points of leakage it will only remain
to examine the piston rings and should they show
signs of blackening or of allowing gas to escape they
should be replaced with new ones.

Incorrect valve timing is not a probable trouble
unless the engine has been disassembled for repairs.
Each maker of engines recommends certain exact
settings for the opening and closing of the several
valves but unless an instruction book is at hand these
settings cannot be known. However, the valve timing
may be checked in a general way according to the
following principles: Selecting any one cylinder of
the engine it will first be necesasry to determine the

386 AUTOMOBILE IGNITION

point at which the piston reaches top center. The
exhaui^t valve should close either at top center or
immediately afterward and as soon as the exhaust
has closed, or, in some cases, simultaneously with the
closing of the exhaust, the inlet valve should open.
With the continued rotation of the flywheel the inlet
valve should close at some point within 15 to 30
degrees after the next bottom center has been passed.
The flywheel may then be rotated until top center is
again reached and after having passed this point the
exhaust >valve should be found to open a considerable
time before the piston reaches the bottom of this
stroke.

Should it be found that the valve timing is mark-
edly at variance from the outline given, an adjust-
ment should be made either by means of the tappets
or by altering the relative positions or the meshing
of the engine timing gears.

The clearance between the end of the valve steins
and the part of the operating mechanism which bears
against the stems should be correctly adjusted. The
space at this point should not exceed the thickness of
a sheet of writing paper and should a great excess
of clearance be found it may be safely assumed tha^
a correction will result in great improvement pf
engine operation.

The strength or tension of the valve springs may
be either too little or too great. If the springs are
too weak it will result in missing at high engine
speeds because the valve heads will not be brought
to their seats with sufficient speed to correspond with
the operating speed of the engine. Weak valve
springs may be located by the process of inserting a
screw driver blade between the coils of the spring

TROUBLES AND REMEDIES 88T

and then turning the screw driver so that the spring
is compressed. If this results in ^better operation of
the engine the springs should be permanently
strengthened either by means of washers placed over
the stem at one end or by replacing with a new
spring. Should the valve springs be too strong it
will result in forming grooves either on the face of
the valve, on its seat, or on both. These grooves will
prevent prompt seating of the valve and will cause an.
intermittent missing at practically all engine speeds.

TESTING METHODS AND EQUIPMENT

As in any other work that is to be performed speed-
ily and with accuracy, ignition testing and repair
require the use of instruments adapted to this kind
of work. Among these instruments the most impor-
tant ar^ voltmeters, ammeters, and circuit testers.
Ammeters are but little used in ignition testing,
while voltmeters and circuit testers are of great
Usefulness.

The internal construction of an ammeter, such as
used for testing purposes, is similar to that of a volt-
meter. In addition to the parts included in the
voltmeter, an ammeter contains a short length of
heavy conductor through which passes the greater
part of the current to be measured. Two forms of
ammeters are shown in Figure 170. The form at
A carries the heavy conductor called a shunt within
its housing, while the form shown at B is practically
a voltmeter and by means of an accurately calibrated
external shunt the amperage of a circuit to be tested
is measured by the voltage difference between the two
ends of the shunt conductor. A self contained

388

AUTOMOBILE IGNITION

ammeter, or the external shunt when used, is always
connected in series with the circuit being worked
upon so that all of the current will pass between the
points X and Y of the cables shown in Figure 170.

The voltmeter is designed for measuring the differ-
ence in electrical pressure or the volj^ge between any
two points of an' electrical current or between the
terminals of a source of current. By means of this
instrument electrical troubles such as short circuits,
accidental grounds, poor contacts, points of high

SHi/NT

Flgrure 170. — ^Ammeter and Voltmeter Construction. Left:
Self Contained Shunt. Rigrht: External Shunt.

resistance or open circuits may be quickly and defi-
nitely located. One of the reasons for the great use-
fulness of the voltmeter is that its indications are
practically independent of the amount of current
flowing and under normal conditions of operation, as
well as in the abnormal conditions occasioned by any
kind of high resistance or an open circuit, there is
cither a very small flow of current or no flow at all.
In such cases the readings on an ordinary ammeter
would be too small for practical purposes.

TROUBLES AND REMEDIES

38&

The principle involved in the use of the voltmeter
in locating open circuits or points of high resistance
may be understood by reference to Figure 171, in
which is shown at A the battery having its terminals
connected with each other by a conductor and at B
the same battery with the ends of the conductor sepa-
rated. If the condition shown at A is considered as
normal, that is, if it is desired that current should
flow between the terminals of the battery and if the

Figure 171. — Testing for Open Circuit with Voltmeter.

voltmeter is attached as shown, but very small pres-
sure will be indicated, this slight voltage being due
to the small resistance of the conductor between the
points of attachment for the voltmeter leads. If, as
at B, the circuit should accidently be opened, thus
producing an abnormal condition, then the voltage
reading will be practically equal to the full voltage
of the battery because there will be no other connec-
tion between the battery terminals except that
through the voltmeter itself. If then, the normal
reading ought to be very small, as at A, and it should
be found that it nearly equals the battery voltage,
such as the comparatively higliTeaAm'^'^^^^"^'^'^"^'*

290 AUTOMOBIL.B IGNITION

then the indications are that an open circuit or a
point of very high resistance exists.

Reference to Figure 172 will make clear the use of
the voltmeter in locating short circuits or accidental
grounds in the ignition system. The voltmeter should
first be inserted in the circuit as shown, preferably
at a point near the battery. All switches should then
be placed in their open or **oflf'' position so that with
normal conditions there will be no flow of current and
because of the open circuit caused by the switches
there should be no voltage reading. If there exists
a short circuit or a ground through which a leakage
of current is taking place, there will be a voltage read-
ing and when the trouble is located and remedied the
voltmeter needle will drop to zero. Referring agaiii
to Figure 172; X, Y and Z indicate instruments or
parts in the ignition circuit. If we now assume that
a short circuit exists, as shown by the dotted line A,
and we assume that part Z represents the switch, it
win be clear that a voltage reading will be given
because current is free to flow through the short cir-
•cuit. Removal of the wire from the terminal 6 will
•cause no change in the reading and neither will
removal of the wire from terminal 5. However, in
continuing the test, should the wire be removed from
terminal 4 the voltage reading will disappear because
the circuit has now been opened. This will indicate
that the trouble exists between the point from which
a wire is now removed (4) and the last point of
removal (5). Should an accidental ground exist in
part Y, as shown by the dotted line B, the removal
of a wire from terminals 6, 5, or 4 will still allow the
voltage reading to remain, but removal of the wire
:from terminal 3 will cause the voltage to drop ta

TROUBLES AND REMEDIES

391

zero, indicating that the trouble existfi^ between the
point now detached (3) and the point of last
removal (4).

Referring to the outline diagram shown in Figure
173 the voltmeter would be used for locating open
circuits or points of high resistance by making attach-
ments of the voltmeter leads to the terminals of the
various parts or to the ends of a wire in which trouble
is suspected, but without inserting the meter in the
circuit as was done in the foregoing test. Thus, to
test the line between the battery and switch the volt-

Figure 172. — Testing for Grounds and Short Circuits with

Voltmeter,

meter would be connected between points C and D
as shown. A full voltage reading would indicate an
open circuit : a reading nearly as high as that of the
battery would indicate that a point of high resistance
lies between points C and D while a zero reading or
a very low reading indicates that the line C-D is in
proper operating condition. A similar test may be
made on lines E-F, G-H, J-K, etc.

To test the switch, the voltmeter would \s<^ ^^^rc^-
neoted io points D and E; to t^^t Wv^ q,^-{S. S^cv^ x^^\jst

392 AUTOMOBILE IGNITION

would be connected between F and G and to test the
breaker between J and H, With the switch closed,
while the voltmeter is attached between its terminals,
a full voltage reading indicates that the switch is not
closing the circuit ; with the breaker closed a full volt-
age reading indicates that breaker is not completing
the circuit while with the attachment made to the coil
a full voltage reading indicates a'n open circuit in
this part. In any of the above instances a low read-
ing, or a zero reading indicates that the parts being
tested are carrying the current and are, therefore,
iiL normal operating condition.

An open circuited or defective ground connection
would be located by attaching one terminal of the volt-
meter to the frame of the car or to some point of the
metalwork connected with the engine and with the
lead from the other terminal of the meter touching
the battery terminal B if the defect is suspected at
the ground connection A ; or by touching the breaker
terminal J if the trouble is thought to be at ground
connection K.

The voltmeter ' would be used for locating short
circuits or grounds in the system shown in Figure
173 by attaching the meter in series between one of
the battery terminals and the wire which ordinarily
connects with that terminal; that is, the attachment
would be made between battery terminal B and the
battery end of the wire A-B, or between the terminal
C and the battery end of the wire C-D, in a way simi-
lar to that shown in Figure 172.

With the voltmeter thus connected the ignition

switch should be opened and the position of the hand

on the voltmeter dial then noted. Should the hand,

by leaving the zero mark, indicate t\v.3A. electrical pres-

TROUBLES AND REMEDIES '393

sure is present, the procedure outlined in a preceding
paragraph for this class of trouble should be followed ;
namely, removal of the wires from their terminals
one at a time, starting with the connection farthest
from the battery and working back to the battery.
This would call for removal of the ground connection
K to start with, or, in case this is not convenient or
if the connection J-K is known to be in good order,
then the first removal would be at H. If, with con-
nection H opened, the voltmeter hand drops back to

a/t£fiK£/(

Figure 173. — Testing for Open Circuits and High Resistance

with Voltmeter.

zero it indicates that a short circuit or an accidental
ground exists in the breaker mechanism. If the volt-
meter reading is not changed by this removal, the
wire should be replaced at H and the connection G
should be opened. If this removal causes a zero read-
ing on the meter it indicates trouble in the line G-H.
All of the connections should be opened and re-con-
nected in the order G, F, E, D and C as shown in
Figure 173, and when any removal causes a zero
voltmeter reading the trouble will be, i5xvixA\i^\^^^'s^

394 ' AUTOMOBILE IGNITION

the point then disconnected and the last point at
which the circuit was broken without causing a zero
reading. Should no trouble be found between the
battery and connection K, then the same method
should be followed with the other side of the circuit,
starting farthest from the battery (at A in Figure
173) and working back as explained.

The foregoing directions are, of course, general and
apply to the system shown in the figure. The prin-
ciple will remain the same regardless of the equipment
being handled and, with the aid of a wiring diagram
which applies to the system in hand, the work may be
quickly accomplished.

On cars equipped with battery ignition it will be
found in practically every case that an electric start-
ing and lighting system is also present. Connecting
the voltmeter to the battery as directed, would then
include the starting and lighting system in the field
of operation and it is not always desired to spend
time on this part of the equipment. In such a case,
in place of attaching the voltmeter directly at the
battery it may be attached between two wires or con-
ductors, making the connection at the end nearest the
battery and of the line which supplies the ignition
current. That is, the wiring should be followed away
from the battery until a line branches off, leading to
the ignition switch, the coil, a fuse, or some other
member of the ignition system. The point at which
this line leaves the starting and lighting wiring should
be opened and the voltmeter inserted. Tests as
described should then be made, considering that the
voltmeter is the beginning of the ignition wiring,
just as in the illustrations the battery is considered
as the beginning.

TROUBLES AND REMEDIES 395

Voltmeters are generally constructed witli the zero
mark at the left hand end of their dial as shown at
B in Figure 170 and with such an instnlment it is
necessary that the connection from its terminals be
made with reference to the polarity or direction of
flow of the current. Should the connection be wrongly^
made the meter will show no reading under any con-
ditions and the connections should be reversed.
Ammeters are often made of the zero center type as
shown at A in Figure 17©, such an instrument reading-
correctly regardless of the direction of current flow
because of its hand moving to the left for one polarity
and to the right for the other.

Figure 174. — Circuit Tester from Drop Lamp Cord.

The Circuit Tester, — ^The circuit tester, as shown in
Figure 174, consists of two insulated leads ending in.
contact points and cut into one side of the line lead-
ing to any ordinary electric lamp used with a 110
volt lighting circuit such as found in most shops. An
improvised tester of this type may be made by cutting
one of the wires leading to a drop light and using the
two cut ends as tester points.

It will be evident that if the two points should now
be brought together the lamp will l\^\vl\ ?ySs.<^.»*<feai^>S.-

396 aut6mobii1e ignition,

, the two contacts be touched to different points of the
wiring or of the electrical equipment which are con-
nected by a conductor of any kind, the lamp will like-
wise light. Therefore, if the tester contacts are
placed on two points of the ignition system and the
lamp lights, it will indicate that there is a circuit
between these places being touched ; while if the lamp
does not light, there is no circuit between them.

In using the circuit tester ^it will always be best to
do so with the help of a wiring diagram. From such
diagrams it will be learned that certain portions of
the circuits are generally grounded. Before testing
the wiring for grounds which are accidental, it will be
necessary to remove these normal grounds. If one
side of the battery is grounded this connection should
be separated ; if the lamps are of the grounded type,
the bulbs should be removed, and the grounded side
of the horn, coil, etc., should also be disconnected. If
one of the tester points be now placed on the metal
work of the car and the other touched to the line
remaining attached to the battery, an accidental short
or ground will be indicated by the lamp's lighting.
Each wire and part may be tested by disconnecting
it at the terminals and, with the tester in contact
with the metal work, touching either end of the sus-
pected wire with the other test point. If the lamp
lights it indicates a ground.

To test for short circuits between two wires or
parts that are normally insulated from each other it
is only necessary to touch one test point to one of the
wires or parts and the other test point to the remain-
ing wire or part. Lighting of the lamp indicates a
short circuit.

If it is thought that a wire or lead is broken it may

TROUBLES AND REMEDIES

397

be tested by placing the two test points with one in
contact with each end of the lead. If the lamp lights
it indicates a complete circuit, while if it fails to
light it indicates a break.

Open circuits may be located in any conductor or
lead and in parts which are required to make an
electrical connection, such as the switches, by the
simple expedient of making a temporary connection
around the part or line to be tested with a length of
wire having both ends clean and bright. Thus, if any
one wire is thought to be broken or making a poor
connection, the extra length may be connected to
the two terminals to which the ends of the wire being

Figure 175. — Adjustable Spark Gap for Ignition Testing.

tested are attached. If, with the additional wire in
position, operation becomes normal, it indicates an
open circuit between the terminals being touched.

Tlfie Spark Gap, — The distance that an ignition
spark will jump through the air is an indication of
its ability to ignite the mixture. In order to be use-
ful for igniting the mixture a spark should pass
through from one-quarter to one-half inch of air
space. Such a test may be made by means of the
adjustable spark gap shown in Figure 175. The ends
of the high tension circuit are to be attached as shown
or, as will generally be the case, either gap end

398 AUTOMOBILE IGNITION

4should be grounded to the metal of the car whose
ignition is to be tested, and the high tension lead from
the coil or from the distributor should be connected
with the other side of the spark gap. With the
engine running or being cranked, or with the breaker
•contacts separated by hand, the spark strength may-
be tested in a relative way by gradually opening the
^ap until sparks cease to pass, or, if none pass to start
with, by gradually closing it until they do jump the
Air space. A spark less than one-quarter inch long
indicates weak magnets, providing all other items
have been checked.

In the case of a miss which is unusually difficult
to locate and which affects one or more certain cyl-
inders, a test may be made while running on the road
by means of a set of auxiliary spark gaps as illus-
trated in Figure 176.

The gaps are made from slightly pointed pieces of
round or strip copper, brass or steel and are mounted
on a board as shown, a sufficient number being pro-
vided to handle engines with the maximum number
of cylinders that may be expected in the shop. The
distance between the points should not be greater
than 1/32 inch so that a minimum of extra resistance
is inserted in the circuit. One of each of the pairs
of gaps should be provided with terminals to which
may be attached the ends of the wires which are
removed from the spark plugs and which come from
the distributor D. The other terminal of each pair
should carry a fairly long length of well insulated
wire having its free end provided with a connection
to fasten to the spark plug in place of the distributor
lead removed. With such a set of gaps in circuit the
engine may be started and run as usual. For each

TROUBLES AND REMEDIES

399

spark passing at the plug in the cylinder a spark will
pass across the corresponding auxiliary gap and this
outside spark may be watched for missing. It will be
found best to connect the gaps with the distributor
leads so that the sparks play from one end to the other
of the board, passing from each gap to the adjoining
one in succession, because it will then be easy to fol-
low the jregular action with the eye and to note any
interruption or missing that may be present. This,

Figure 176. — Series of Spark Gaps for Running Tests.

of course, means that one point of each gap will be
connected with the spark plugs in the order of the
cylinders' firing.

With the engine in operation the regularity of the
sparking at any gap will indicate the regularity, or
lack of it, of the sparks within the corresponding
cylinder. The lines from the board may be made of
sufficient length to allow carrying the set on the seat
or floor beside the driver during a road test so that
actual operating conditions may be obtained. It

400 AUTOMOBILE IGNITION

will be found an improvement to shade the board
with a hood so that the sparks may be observed in
comparative darkness or to blacken the board itself.
It should be noted in this connection that a majority
of black paints are good conductors because of their
carbon and it will then be necessary to insulate the
gaps from the painted surface.

Miscellaneous Tests. — The polarity or direction of
flow through any circuit may be determined by insert-
ing the two ends of the circuit, or the two wires
between which current flows, into water to which has
been added a small amount of acid to form an electro-
lyte. With the passage of current, bubbles of gas
will rise from the end of the wire attached to the nega-
tive side of the current source, or, in other words,
from the negative wire, as shown in Figure 177.
Another polarity test may be made by touching the
two wires to a strip of moistened red litmus paper,
•. when a blue spot will appear at the negative wire.

Should a miss occur persistently in one certain
cylinder, or in a certain two or more cylinders, it
may be possible to locate the fault by interchanging
some of the parts from the circuit of the troublesome
cylinder with similar parts from the circuits of cyl-
inders known to be operating properly. Thus, if the
spark plug from a cylinder that is missing be changed
for one from a good cylinder, and if the miss then
occurs in the cylinder that was formerly in good
order and not in the one first in trouble, it is evident
that the plug is at fault. Similar interchanges may
be made with coils and other units in some systems.

In order to locate which of the engine cylinders is
missing its explosions, the spark plugs should be short
circuited, one after another, by means of a wood

TROUBLES AND REMEDIES

401

handled screwdriver or hammer having its metal por-
tion so held that it touches the terminal on top of the
spark plug electrode and at the same time touches
the metal of the spark plug shell or of the cylinder*
This test should be made with the engine runnings
and if this short circuiting causes a noticeable differ-
ence in operation, or slowing of the engine, the plug
and high tension line thus being tested is in good
order and doing its work. If, however, the short cir-
cuiting makes no difference in the engine's operation,
then no spark was passing in that plug and the trouble
may exist either in t\e plug itself or in any part of

Figure 177. — Testing Polarity of Wire Ends in Water Bath.

the secondary circuit from the plug back to the dis-
tributor rotor.

It may usually be determined whether or hot any
one cylinder is firing by slowly opening its priming
or pet cock while the engine is running. If a sharp
pop or explosion is heard, or if flame is seen to emerge,
the cylinder is working, while if nothing more than
a hiss is heard, that cylinder is at fault.

Magneto field magnets are not conveniently tested
with the facilities ordinarily at hand. A magnet of
usual size when properly magnetized will lift a piece
of iron or steel weighing from ten to fifteen pounds.

402 AUTOMOBILE IGNITION

A small spring balance may be used as shown in
Figure 178 and in connection with an iron bar S to
test the pull of a magnet. Should 'the magnet be
found very weak it may be put in -working condition ,
by means of a remagnetizer such as may be purchased
from electrical or automobile supply houses or which
may be made as follows :

Two magnet cores, each about five inches high and
1 3/4 inches in diameter should be constructed of
<;lean lengths of iron wire bound together and dipped
in solder. These cores should be mounted on an iron
base (not one of steel) and should then be covered
with a layer of fibre or enameled cambric insulation,

« s; 5 «• o "N ^^

Figure 178. — Testing Strength of Magnets with Spring

Balance.

after which they are to be made into electro magnets
'by winding around each core 500 feet of No. 16 gage
insulated copper wire, taking care to have the direc-
tion of winding as shown in Figure 179. With this
remagnetizer connected to four six volt storage bat-
teries in series, or to any number of batteries provid-
ing 24 volts, and with a knife switch in the circuit as
shown, the arrangement is ready for use.

The magnet to be charged should be placed on the
magnetizer, with the positive pole of the magnet in
contact with the negative of the magnetizer, and
with the negative of the magnet in contact with the

TROUBLES AND REMEDIES

403

positive of the magnetizer. The operation is then
completed by closing and opening the switch a num-
ber of times; or by drawing the magnet away from
the magnetizer and replacing it several times, or by
tapping the magnet with a small hammer while it
is in place on the magnetizer ; the idea being to cause
a magnetic disturbance sufficient to permanently affect
the steel of the magnet.

^r+

V///////// //////A

ffi R m PI m R m *

Figure 179. — Construction of Magnet Recharger.
IGNITION FAULTS AND REMEDIES

Wiring and Switches. — The methods of locating the
more common troubles in the wiring system have been
explained in a foregoing portion of this chapter
under the heading ** Testing Methods and Equip-
ment." It might also be mentioned that it is some-
times possible to locate a short circuit by running
the engine in a very dark place, when the trouble
may be seen by means of a bluish flicker or a small
spark.

404 AUTOMOBILE IGNITION

/ It will be found in some cases that the addition of
extra equipment has brought about a double ground;
that is, the added equipment may have been grounded
through the negative side when some other part of
the system is already grounded through the positive,
or vice versa. In -all such cases it will be well to care-
fully follow the wiring. diagram that applies.

It is not best to run several high tension wires
through a length of tubing, or to run some of the high
tension wires in the same tube with others carrying
low tension current because of the induction that
may take place from one to anothei* causing a weak
spark to occur in the wrong plug and to sometimes
have heat enough to ignite the mixture. The high
tension line from the coil to the distributor should
never be run through a tube with the spark plug
lines, but all of these secondary leads should be sepa-
rated from each other by at least y^ inch of space.

In looking for wiring troubles it should be remem-
bered that if the fault is in but one cylinder, or if it
is found in only certain cylinders, the trouble is in the
high tension system between the distributor rotor
and the cylinder spark plugs of those units that do
not operate properly. If the trouble occurs in all
cylinders* or is irregular in all cylinders the trouble
is in the low tension system or in the parts of the
secondary system between the distributor rotor and
the battery line.

In making an examination of the wiring system
the following points should be checked : See that no
parts are out of circuit because of loose or broken
wires or because of short circuits between terminals,
see that no fuses are burned out in case the system
contains these members, test the suspected lines for

TROUBLES AND REMEDIES 405

Breaks under the insulation by moving the wire and
by bending it back and forth, see that the spark plugs
wires on a four cylinder engine are not interchanged
between cylinders two and three because of a firing
order different from that assumed, and see that the
lines between the breaker and the distributor are not
longer than necessary.

Breaker. — It has already been mentioned that
excessive oiling of the breaker is responsible for a
great many troubles and for shortening the life of the
contacts. The pivot bushing or bearing for the arm
should never be oiled, and unless it is known that the
cams are designed for the use of oil, lubricant should
never be applied to these parts. A sticking breaker
arm, due to gummed oil,. will cause sparking, pitting
and burning of the contacts.

Should it be found that a miss occurs more at low
engine speeds than at high and more with a retarded
spark than with it advanced, the gap between the
contacts when separated should be made greater. If
the miss is more pronounced at high speeds or with
an advanced spark then the gap should be made
smaller. The time of contact and the flow of current
through the coil is increased by making the gap
smaller and increased by making it larger. A weak
battery can oftentimes be used by lessening the gap
between the contacts, while current will be econom-
ized by making the gap greater.

Before making an adjustment, or assuming that it
is necessary, the contacts should be cleaned with
gasoline until white. Whenever possible the inspec-
tion should be made by removing bodily the parts
carrying the contacts rather than by unscrewing the
points and thus changing the adjustment. After an

406 AUTOMOBILB IGNITION

adjustment has been mlade it will, almost always be
necessary to clean and dress the contacts so that they
come together properly. After they have been
dressed, a piece of clean cloth should be drawn
between their surfaces to remove any particles of
dust or filings. It is essential that the faces of the
contacts be brought into line with each other, either
by revolving the adjustable point or by bending one
of the screws.

In testing the adjustment or gap it should bo
noted that a certain amount of pitting may prevent
the introduction of the thickness gauge, and yet may
not be harmful to the operation. If the pits on one
contact just correspond with elevations on the oppo-
site contact, the operation will probably be satisfac-
tory and dressing of the surfaces will not be required.
Should the contacts be dressed it will not be neces-
sary to completely remove every trace of pitting, for
it is impossible to make the operation of dressing
provide contact over more than a small percentage of
the total area and the hammering action while the
breaker is in operation makes a better job than any
amount of filing.

It is possible that faulty operation of the breaker
is due to breakage or loosening of the spring wtich
operates the arm carrying the movable contact and
this point should be examined. It is also possible
that the metal of the contact points has been spoiled
by allowing the ignition switch to remain turned on
with the engine idle and while the breaker is in the
closed position. Complete descriptions of the various
forms of battery and magneto breakers are given in
Chapters Four and Nine.

Distributor. — Both the inside and outside surfaces

TROUBLES ANX) RBMEDIEIS 407

of the distributor should be kept clean and the track
of the rotor should be kept smooth as explained in
this chapter under the heading of '* Lubrication,^'
Recurrence of excessive carbon deposit and cutting
of the edges of the segments may indicate that the
distributor is being driven in the wrong direction,
of rotation, although this is manifestly a remote^
possibility.

The insulation of the rotor may be tested by hold-
ing the end of the high tension cable coming from the
coil against the brush or the metal portion of the
rotor, then, by operating the breaker, causing a high
tension current to pass. During the breaker opera-
tion the insulated portions of the rotor should be held
close to some metal part of the engine. If any spark
passes through the insulation the rotor is defective.
With a jump spark type of distributor the gap
between the rotor segment and the stationary seg-
ments or pins for the spark plug wires should be
1/64 inch or less.

The small springs which give the required pres-
sure to brushes in the distributor rotor or cap, and
in fact, the springs for any similar brushes, should
have very light tension and this tension should never
be increased. Just enough pressure is required to-
cause the ends of the brushes to remain in contact
with the path over which they travel or on part»
with which they should be in contact. Too great
tension on these springs will cause excessive wear and
will bum and blacken the parts affected because of
the friction generated while the engine is running.
The brushes themselves should never be cramped or
jammed into place. It is bad practice, although quite
the usual thing, to pull these brush springs out of

408 AUTOMOBILE IGNITION

shape, thinking thus to increase the tension and
make better a contact which is ahnost always good
enough to do the work perfectly. The setting or tim-
ing of magneto type distributors should be checked
in accordance with the instructions *given in Chap-
ters Four and Nine. The safety spark gap, which is
in circuit with the distributor, should be examined for
broken insulation or for short circuiting.

CoU. — The condition of the coil may be determined
by removing the line leading to the center of the dis-
tributor and, while holding the free end of this line
from one-quarter to one-half inch from the metal of
the engine, operating the breaker contacts with the
fingers. On cars provided with a starting button for
producing a spark in the cylinder ready to fire, the
coil may be tested by operating this button. The
spark should jump at least 5/16 inch in the air.

The windings or internal connections of the coil
may be broken, loose or burned out, or they may be
short circuited on each other or on the housing.
Should such troubles be suspected testa may be made
with the aid of an internal wiring diagram for the
particular unit being handled. Examination should
be made to make sure the coil is attached to a bat-
tery of the correct voltage or to a number of cells that
will give this voltage.

On cars using a number of coils, one for each cyl-
inder^ it is possible that induction may take place
from one coil to the adjoining ones. Such a condition
may be remedied by inserting strips of soft iron
between the units affected.

Condenser. — Defects in the condenser will cause
severe arcing at the breaker contacts, while if the
condenser is out of circuit, oi: if the wires between

TROUBLES AND REMEDIES

409'

the condenser and the breaker are of excessive length,
the spark will be weak and thin. In making tests
of the condenser they should first be applied with the
unit cold and afterward repeated with it warmed ta
about 180 degrees Fahrenheit.

To test for a short circuited condenser, the con-
denser should be disconnected, or if carried in the
coil, the coil should be disconnected. The circuit

Ciiecwr

Figure 180. — Testing Condenser with Circuit Tester
(Dayton Engineering Ltaboratories).

tester should be used while attached to a 110 volt
lighting system. If the test lamp lights, the con*
denser is short circuited. If the ignition system uses
a grounded primary circuit, one side of the circuit
tester should be connected to the metal part carry-
ing the condenser and the other side to the base of
the coil. This test will not be so reliable because it

410 AUTOMOBILE IGNITION

the primary winding of the coil should be grounded,
the test lamp will light the same as with a short
circuited condenser.

If separation has occurred between the layers of
the condenser its capacity will be very low. The
capacity may be tested by means of the circuit tester
used with a 110 volt direct current circuit. Make
and break the contact between the test line and the
condenser terminals and note the spark obtained. If
a good spark appears the condenser's capacity is
satisfactory. If, in this test, an alternating current
circuit must be used for the circuit tester a good
spark may sometimes be obtained, but sometimes will
not be obtained, thus making the test unreliable": A
complete description of the condenser is given in
Chapter Four.

Spark Plugs. — A majority of spark plug trouble
comes from deposits of oil or soot on the surface of
the insulation either inside of the shell or on the out-
aide. Separable plugs may be cleaned by removing
the core and wiping the insulation with a kerosene
moistened cloth or with a soft brush until it is clean
and bright. The same should be done to the part of
the core extending outside of the shell. The condi-
tion of the shell and metal parts as to cleanliness has
Tery little to ^do -with the operation of the plug, but
is absolutely essential that the insulation should be
free from conducting matter of all kinds. One piece
plugs may be soaked in kerosene and then cleaned
with a thin scraper or with a soft brush. Whenever
possible it will be advisable to soak the plugs over
night in kerosene before cleaning them.

Spark plugs with porcelain or stone insulators may
lave cracks so small that it is almost impossible to

TROUBLES AND REMEDIES 411

detect them. Such insulators may have been cracked
because of ^:cessive tightening of the packing nut,
after which the unequal rates of expansion of the
insulator and the metal shell will cause fracture. The
insulating members of mica plugs will probably
become oil soaked in time, after which it is an economy
to replace them with new ones, for cleaning can never
remove the oil that has worked in between the layers.

The gap between the spark plug points should be
from 1/64 to 1/32 inch, small for use with magnetos
and larger for use with battery systems. Should
missing occur mostly with small throttle openings and
at light loads it indicates that the gap is too small and
should be made wider. If the missing occurs prin-
cipally at heavy loads and low speeds it indicates that
the gap is too great and it should be made smaller.
Too wide a gap may cause a popping in the carbu-
retor which will be somewhat similar to that due to
too thin a fuel mixture.

The gap should be altered by bending the electrode
that is fastened to the shell, rather than the central
electrode, whenever this is possible; thus avoiding
mechanical strains on the insulator. The ends of the
electrodes should be kept blunt and rounded in place
of pointed. A complete description of spark plug
construction is given in Chapter Five.

Batteries, — The care of the storage battery is a sub-
ject important enough for a whole book to be written
about it. The battery is primarily a part of the
lighting and starting system, although used as a
source of ignition current. The storage battery
should be kept clean and a proper level of electrolyte
maintained by the addition of distilled water twice
a month. A properly charged battery will provide

412 AUTOMOBILE IGNITION

satisfactory ignition with the balance of the ignition
equipment in good condition. If the battery does
not remain properly charged, the charging system, the
lighting system or the starter are at fault and very
rarely the ignition system. More detailed information
on the storage battery is given in Chapter Three.

In using dry cells it will be best wiien possible to
use two sets connected in series-multiple rather than
the single set generally shown in the wiring dia-
grams. Care should be used to see that the covers
of dry cells are intact and that the cells are so placed
on the car that the negative (outside) terminals are
not short circuited or grounded. Dry cells are also
described in Chapter Three.

Magnetos. — A magneto should not be tested unless
fully assembled because of danger to the insulation
of the windings. A simplel test of a high Jtension
machine may be made by resting the blade of a screw-
driver on a metal portion pf the instrument and hold-
ing the point about one-quarter inch from the sur-
face of the collector ring while the armature is turned
at fair speed. A spark indicates that the primary
circuit and parts carrying this circuit are in good
order, also that the high tension winding on the
armature is working correctly; or in other words,
the trouble, if in the magneto, lies between the col-
lector brush and the spark plug line terminals on the
distributor.

All brushes of the magneto should have proper
spring tension and should be whole and unbroken in
any way. The rings or surfaces with which the
brushes are in contact should be clean and bright.
These brushes will be found at the collector ring, in
the distributor, in the breaker and back of the breaker

TROUBLES AND REMEDIES 413

base plate, and at some point along the length of the
armature to provide a ground connection independent
of that secured through the bearings. The number
and location of the brushes will depend on the make
and type of instrument.

Care should be exercised in removing and handling
the magnets. If they are to be taken oflE the magneto,
an iron or steel keeper should be placed between their
poles and allowed to remain there until the magnets
are replaced. If the armature is removed from the
magneto, keepers should likewise be placed between
the pole pieces. In replacing magnets on the mag-
neto the workmen should make sure that all negative
poles are on one side and all the positives together
on the other side, on which side are the negatives,
and which the positives being immaterial. If one or
more magnets are reversed with reference to the
remainder, the magneto will not produce a spark.

The magneto drive parts should be examined for
too much play which will affect the timing, for dis-
connected parts and for slipping of any friction
couplings or set screws. The armature shaft should '
be moved to note whether any excessive play has
developed, and should such looseness exist, the bear-
ings must be adjusted or replaced with new ones..

SYSTEMATIC TROUBLE LOCATION

The ''hit-and-miss'' method of looking for ignition
trouble is wasteful of time and not productive of
satisfactory results any more than in any other kind
of work. Certain troubles cause certain symptoms
which may generally be easily recognized. If the con-
nection between the symptom and the trouble is known

414 AUTOMOBILE IGNITION

to the workman he can quic^y determine which parts
require attention and can look only for probable
troubles.

In the following outline of troubles- these symptoms
have been adopted as a guide :

Engine Will Not Start.

Engine Starts Hard.

Certain Cylinders Not Firing.

Irregular Miss in Some Cylinders, But Not All.

Irregular Miss in All Cylinders at All Speeds.

Irregular Miss in All Cylinders at Low Speeds.

Irregular Miss in All Cylinders at High Speeds.

Lack of Power and of Flexibility.

Any case of ignition trouble may be classified as
causing some one of these symptoms and each symp-
tom calls for an inspection of certain parts, these
parts being listed in the Tables at the left hand side.
Below the name of each part is then given a list of
the most probable troubles and also suggestions for
the work required. This list is not complete because
certain troubles are extremely rare, but those given
will cover the great majority of all cases presented
for solution and will provide a base from which the
repair man may work toward the development of his
own methods of systematic work.

TROUBLES AND RBMEDIES

415

ENGINE WILL NOT START

Switch —

Turned off.

Loose terminal connections.

Internal open circuits.

Fuel —

Tank empty.
Feed lines stopped.
Fuel feed not working.
Carburetor Jets clogged.

Fuse —

Burned out (on grounded bat-
tery systems only).

Battebt —

Run down.
Grounded or shorted.
Water level low.
Dry cell covers broken.
Dry cell terminals touching each
other or box sides.

WmmG —

Examine line from coil to dis-
tributor center.

Test primary lines for open,
short or grounded circuits,
for high resistance and poor
connections.

Grounded battery system may
have live side also grounded
through some of the acces-
sories.

Magneto switch line may be
grounded.

Resistance —

Broken, disconnected or burned
out.

fiBEAKEB —

Arm sticking.

Spring loose or broken.

Use circuit tester.

Switch left closed.
Use circuit tester.

Use wood separators.
Tape if necessary.

Use circuit tester.

Ground other side of
accessory.

Remove wire from
magneto for test.

See diagrams.

Clean pivot beartng.

416 AtlTOMOBILB IGNITION

Drive —

Loose, destroying accuracy of See instructions for
timing. timing.

€oii/—

Disconnected or burned out Use circuit tester.

Hagneto —

Magnets reversed. Test polarity.

Ground brush for- breaker or
armature defective.

TROUBLES AND REMEDIES

417

ENGINE STARTS HARD

Battbby —

Run down.

Grounded or short circuited.
Water level low.
Dry cell covers broken.
Dry cell terminals touching each
other or box sides.

Cabbubetob —

Improperly adjusted.

Breaker —

Contacts dirty or out of line.
Arm binding.

Pluos —

Dirty, inside or out.

Gap too wide or too small.

Cracked or broken insulation.

Wiring —

Dirty or loose terminal contacts.
Condenser out of circuit.

Valves —
Leaking.
Wrongly timed.

Switch —

Internal contacts dirty.

DiSTRIBXJTOR —

Dirty, inside or out

IiIagneto —

Magnets weak.

Magneto mounted on iron or
steel base.

Switch left closed.
Use circuit tester.

Use wood separators.
Tape if necessary.

Set 1/32 to 1/64 Inch.

In case condenser is
away from breaker.

Test compression.

Make voltmeter test

Base must be non-
magnetic.

418 AUTOMOBILE IGNITION

CERTAIN CYLINDERS NOT FIRING

Plugs —

Dirty, inside or out.

Loose or broken insulation.

Too wide gap. Set 1/32 to 1/64 inch.

Loose electrode.

Wjbinq —

Spark plug wire broken, discon-
nected or loose.

Wires to cylinders 2 and 3 in- Should be placed ac-
terchanged on four cylinder cording to firing
engine. order.

DiSTBIBUTOB —

Short circuited through cracked
insulation.

TROUBLES AND REMEDIES

419

Set between 1/32 and
1/64 inch.

IRREGULAR MISS IN SOME CYLINDERS,

BUT NOT IN ALL

Plugs —

Dirty, inside or out.

Broken insulation.

Loose electrode.

Gap too wide if missing at low

speeds.
Gap too small if missing at high

speeds.

Wjbinq —

Spark plug wires have poor con-
nections, breaks under insula-
tion or are loose.

Wire from coil to distributor
center in tube with plug
wires.

DiSTKIBUTOB —

Dirty inside or out.
Broken insulation.

Coils —

Induction from one to another. Place soft iron sheets

between units.

Central high tension
line should be sep-
arated from others.

420

AUTOMOBILE IGNITION

IRREGULAR MISS IN ALL CYLINDERS
AT ALL SPEEDS

Breaker —

Contacts dirty, pitied, burned

or out of line.
Contact screw or rocker arm

loose.

WiBmo —

High tension line from coil to
distributor loose or broken.

Low tension lines have poor
connections, breaks, shorts or
accidental grounds.

Distance from breaker to con-
denser too great.

DiSTBIBUTOB —

Insulation cracked or broken
away at some points.

Condenser —

Out of circuit

Sapety Gap —

Cover dirty or broken.

CoLLEOTOB Ring —

Dirty or has broken insulation.

CoLLEOTOB Brush —
Sticking or broken.

Magneto Armature —
Bearings loose.

The only high ten-
sion line affecting
all cylinders.

Will affect all cylin-
ders.

Should not exceed 36
inches.

See wiring diagram.

TROUBLES AND REMEDIES 421

IRREGULAR MISS IN ALL CYLINDERS
AT LOW SPEED ONLY

Breaker —

Arm sticking. Clean pivot bearing.

Contact opening too small. See instructions.

Distributor —

Timed wrong with armature. Rotor in wrong posi-
tion.

IRREGULAR MISS IN ALL CYLINDERS
AT HIGH SPEEDS ONLY
Breaker —

Contact opening too wide. See instructions.

Distributor —

Covered with carbon dust or oil

film.
Timed wrong with armature. Rotor in wrong posi-

tion.

LACK OF POWER AND OF FLEXIBILITY

Valves —

Leaking. Test compression.

Too much clearance.
Wrongly timed.

Igiotion Timing —

Wrong setting. See Instructions.

Loose driving parts.

lilAGNETO Mounting —

On iron or steel base. Base should be non-

magnetic.

IGNITION WIRING
In tile following pages will be found wiring di&-
grams which supplranent those in the body of this
book.

Type "P" with Separate Switch.

IGNITION WIRING

rigura tS). — Wiring of Boach Dual Two Spark Magneto.

FIfrure 184. — Wiring of Connecticut Battery System,

AUTOMOBILE IGNITION

IGNITION WIRING

Figure 1ST,— Wiring of KingB\.on Tti-ntloxTOW
MagTietoa. Modela "L." atv4 "^-

AUTOMOiBIL,E IGNITION

Flffure 189. — Wiring of National Tranaformer Coll MctKneto.

WTTlRV-l l( *^2

pDISTRIBUTDR

Figure 190.— Wiring ot Phllbrln Duplex Battery System.

Figure 191.— Wiring of Simma Dual Magneto, Model "SO-IX*

AUTOMOBILE IGNITION

Figure 192. — WliinB of Slmma Dual Masneto. Uodel

INDEX

Adjustment, breaker contact (see name of equipment) . 54

Advance and retard 15, 113, 136

automatic 144

how secured 141

Ammeter, use of 387

Ampere 20

Atwater Kent ignition 81

adjustment 182, 194

advance and retard 189

automatic advance 147

breaker 178

coil and condenser 186, 192

distributor 185, 194

switches 186

timing \ 190, 195

wiring 187, 195, 422

Automatic advance / 144

Atwater Kent 147

Delco 148, 150

Eisemann 151

Sevison 146

Westinghouse 153

Ballast coil 85

Base, magneto 320

Battery, dry 43

ignition systems 47, 156

storage 38

storage, care of 42

trouble 411

Bosch battery ignition 235

coil 238

timing 240

430 INI>BX

magneto Ignition 323

coupling 312

DU type magneto 323

dual type 330

NU type 337

timing 328, 329, 335

wiring 333, 423

2R type 329

Breaker (see name of-Bystem) 50, 63

adjustment 64

arms 61

cams 67

high speed types 65

magneto 297

timing lie

trouble 405

Cable, ignition 108

primary 110

secondary ilO

Cams, breaker 57

Care of Ignition equipment 37S

Cell, dry 4S

storage 38

Circuit breaker 20, 23, 50

insulated or grounded 62

open 24

open, location of 392, 39G

aeries and shunt 22

short 24

short, location of 390, 398

tester 395

Closed circuit system 77

Coll, Ignition 89

Induction 34

trouble 408

Commutator, Ford 257

Condenser 66

location of 69

Coriductors 1ft

Connecticut ignition 225

adjustment 227

advance and retard 229

INDEX 431

breaker 226

coil 88

distributor 228

switch 231

timing 230

wiring 234, 423

Connections, circuit '. . 21

dry cell 45

Contacts, breaker 50, 53

Control of spark advance 16

Core, spark plug 95

Coupling, Bosch 312

Eisemann 311, 318

magneto drive 310

starter 314

Sumter 315

Teagle . , 317

Current, flow of 20

generation of in magneto 273

sources of 35

Cycle of engine 12

Delco ignition j, 156

advance and retard'. 176

automatic advance 148, 150

breakers 65, 156

coils 90, 162

condenser 162

distributor 160

ignition relay ^ 165

resistance unit 164

switches 168

t\^elve cylinder ignition 162

wiring 174

Dimensions of magnetos 321

Distributor (see name of system) 70

jump spark 73

location of 71

magneto - 300

setting of 131, 302

trouble 406

wipe contact 75

wiring of 131

Dixie magneto 371

432 imyEx

Donble Ignition 48

Drive, magneto 308

Dry ceiis 43

Dual Ignltioa 48

magneto 282

Duplex ignition 48

magneto 283

Djnamo 36

1 magneto 341, 352

automatic advance 151

coupling 311, 318

dual magneto 348, 353

timing 350, 353

virlng 347

Blectrlclty 18

production of 33

Electrode, apark plug 97

Electrolyte, battery 40

Electro- magnet I BUI 31

Enetne, four cycle 12

Field of magnet 27

Firing order 126

determination of 128

typical 6 cylinder 129

typical S and 12 cylinder 130

Force, lines of 28

Ford ignition 246

commutator 257

magneto remagnetlzlng 267

magneto voltage 250

timing 269

troubles, ignition 262'

vibrator 251

wiring 253, 259, 261

Gap, breaker, adjustment of. .

safety spark

spark plug

INI>EX 435

Gravity, specific 40

Ground, accidental '. 25

location of 390, 39&

Grounded primary circuit 52-

Heinze magneto wiring 424, 425

High tension magneto 48, 279, 323

Hot tube ignition 10

Hydrometer, battery testing 40

Ignition, battery type 15$

Atwater Kent 178, 191

Bosch 235

Connecticut 22&

Delco 156

North East 241

Remy 197, 208^

Westinghouse 210, 2ia

closed circuit type 77

double 48

dual .7 48^

duplex 48

dynamo 208, 218

• Ford 24e

hot tube la

magneto type 273

Bosch 323, 337

Dixie 371

Eisemann 341

Ford 246^

Remy 355, 365

Splitdorf 359

make and break 10

open circuit type 77

relay, Delco 165

single 47

^ time of 11

timing 113

transformer coil 48

triple 49

two spark 28&

Impulse starter 314

434 INDEX

Induction coil 34

Inductor magneto 363

Insulated primary circuit 52

Insulator, spark plug 92

Interrupter (see breaker) 50

Jump spark distributor 75

ignition 9

K
Kingston magneto wiring 425

L
Xiubrication of ignition equipment 380

Hagneto breaker 297

dimensions, S. A. E 321

distributor \ 300

drive 308

dual type 282

duplex type 283

Ford 24^

high tension 323

ignition 47, 273

Bosch 323, 337

Dixie 371

Eisemann 341

Remy 355, 365

Splitdorf 359

Inductor type 363

magnets for 292

mounting of 320

pole pieces 292, 293

remagnetizer 402

timing 304

transformer coil type 276, 355

trouble 412

true high tension 48, 279

types of 48, 276

Magnet, electro 31

forms of 30

INDEX ^ 435

magneto ! 292

permanent 28

polarity of 27, 29

testing of .401

Magnetic field 27

Magnetism 26

electro 31

Maintenance of ignition equipment '. . . .378

Make and break ignition 10

Master vibrator t > 270

Mea magneto wiring. 426

Mica spark plug 93

Multiple connection of cells 45

Multi-point ignition 289

National magneto wiring 426

North East ignition 241

timing 244

wiring 243

Ohm 20

Ohm's law 20

Oiling of ignition equipment 380

Oldham coupling i . . . 310

Open circuit, location of 392, 396

system of ignition 24, 77

Order of firing 126

Permanent magnet 28

Philbrin breaker 64

wiring 427

Piston travel, chart of. 309

Plug, spark 90

Polarity 20

magnet 27

test for 400

Pole pieces , 292

extended 295

Primary cable I 110

136 INDEX

Relay, Delco ignition 165

Remagnetizer, Ford magneto 267

magneto magnet 402

Remy battery ignition 197

adjustment 198

coil 200

distributor 200

dynamo •. 208

timing 205

wiring , 202

magneto ignition 355, 365

inductor type 365

timing 358

transformer coil type 355

wiring 367, 370

Repair of ignition equipment. '. 378

Resistance, high, location of : 391

unit 85, 164, 213

Retard of spark 15

Rotor, distributor 70

Safety spark gap 86

Series connection • 22

of dry cells 45

multiple connection 46

Set spark 16

Sevlson automatic advance 146

Short circuit 24

location of 390, 396

Shunt connection 22

Simms magneto wiring 427, 428

Single ignition 47

Source of current 35

Spark, advance of 15

advance, automatic 144

coil 35

control - 16

gap, auxiliary 397

gap, safety 86

plug 90

plug, electrode for. 97

INDEX 437

plug, gap of ,. 99

plug, insulator for 92

plug, location of 104

plug, priming type 107

plug, S. A. E. standard 101

plug, separable and non-separable 103

plug, threads for 100

plug, trouble in 410

production of 50

set 16

timing of 136

variable . . . : 16

Specific gravity 40

Splitdorf magneto 359

wiring 361, 428

Starter coil 284

coupling ■ 314

Storage battery (see battery) 38

Strokes of engine 12

Sumter starter coupling 315

Symbols, wiring diagram Ill

Teagle starter coupling 317

Test, magnet 401

polarity 400

Tester, circuit 395

Testing methods 387

Threads, spark plug 100

Timing 113, 136, 304

Atwater Kent 190, 195

Bosch battery ignition 240

Bosch magneto ignition 328, 329, 335

chart for 309

Connecticut 230

Delco i 157

Dixie magneto 377

Eisemann magneto 350, 353

Ford ignition 259

magneto 304

magneto distributor 302

North East 244

Remy battery ignition 205

Remy magneto ignition 358

Splitdorf 362

438 INDEX

valve, Engine 385

Westinghouse 216, 225

Transformer coil 35

ignition 48

magneto 276, 355

Triple ignition 49

Trouble, battery 411.

breaker 405

carburetor 383

coil 408

distributor 406

engine t 383

Ford ignition 262

location of 24, 378, 413

magneto 412

spark plug 410

valve, engine 384

wiring 403

Two spark ignition 289

U
Upkeel) of ignition equipment. . . .^ 378

Variable spark 16

Vibrator, Ford Ignition 251

master 270

Voltage 18

Voltmeter, use of 388

Westinghouse ignition 210

adjustment 211, 221

automatic advance 153

breaker 66, 210, 218

distributor 212, 222

ignition-dynamo 218

resistance unit 213

switches 215, 224

timing 216, 225

wiring 214, 215, 219

Wipe contact distributor 75

Wire (see cable)

INDEX 43&

Wiring 108

Atwater Kent 187, 195, 422

Bosch battery system 237

Bosch DU magneto 281

Bosch dual magneto 333

Bosch duplex magneto 285

Bosch two-spark magneto 290

Bosch two-spark dual 423

Bosch vibrating duplex ignition 288

Connecticut 91, 234, 423

Delco 172-177

distributor 131

Eisemann dual magneto 347

Ford ignition 253, 259, 261

Heinze magneto v 424, 425-

Kingston magneto 425

Mea magneto 42&

National magneto 426-

North East ignition 243

Pfanstiehl starter coil 286, 287

Philbrin ignition : 427

Remy battery ignition 199-209^

Remy inductor magneto 367, 37^

Remy transformer magnetol 277, 357

Simms magneto 427, 428^

Splitdorf magneto 361, 42a

symbols Ill

trouble in 405

Westinghouse ignition 214, 215, 21^

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